Gluten-Free Heirloom Tomato Slab Pie

Feast your eyes on this beautiful gluten free Heirloom Tomato Slab Pie, a rustic tart made in a half sheet pan! This savory delight features a golden, flaky crust that cradles layers of gooey cheese and sweet, caramelized onions. Topping it all off are vibrant slices of heirloom tomatoes, their rich colors and juicy flavors taking center stage. Perfect for sharing, this slab pie is a celebration of summer’s best produce, melding creamy, tangy, and savory elements into each irresistible bite. Ideal for picnics, gatherings, or simply indulging in a slice of seasonal perfection.

You know when someone blogs about something awesome and you’re all–I WANT THAT…like right now? Yeah. That happened to me when I saw this tomato tart that Pioneer Woman made the other day. I had to have it.  So instead I created my own version, hereby dubbed Gluten-Free Tomato Slab Pie.

Recipe and images updated 07/19/24

Unlike 99% of America, I can’t run down to the grocery store and pick up a pre-made, rollable pie crust to make it with. I’ve got to make my gluten-free crust from scratch.  That’s not a problem, really, unless you forget that you are out of say…tapioca starch…when you’ve already been to two different grocery stores to find the flours to make your crust. Maybe you cry a little. Maybe you pour yourself a glass of wine and decide that you are going to drink your dinner. Maybe your husband offers to go and get your missing ingredient. Maybe…just maybe…you can pull yourself together so dinner can be on the table by 8. On a Thursday. On a school night.

What I’m trying to say, folks, is gather up your ingredients beforehand, and plan this supper for the weekend. It feeds a crowd, and it’s an awesome way to use up all of those tomatoes from this year’s bumper crop! No home grown tomatoes for you? No problemo…most markets have pretty baskets of heirloom cherry tomatoes that will work just fine.

How to Make Gluten Free Pie Crust

• 1 1/4 cups tapioca flour
• 1 cup plus 2 tablespoons cornstarch
• 1/2 cup sweet rice flour, plus more for dusting (super fine brown rice flour works well here too)
• 1/4 cup plus 2 tablespoons sorghum flour
• 2 teaspoons granulated sugar
• 1/2 teaspoon sea salt
• 2 1/4 teaspoons xanthan gum
• 1 1/2 cups (3 sticks) cold, unsalted butter, diced
• 4 extra large eggs

Place the tapioca, cornstarch, sweet rice flour, sorghum flour, sugar, salt, and xanthan gum in your food processor fitted with the steel blade attachment. Pulse to combine. Add butter and pulse until your mixture resembles coarse crumbs. Beat the eggs separately in a bowl. Pour through the hole in the top of the processor and pulse until the mixture just comes together in a ball. Flatten into a disk on a sheet of plastic wrap, seal and freeze for 30 minutes to an hour, or until firm. (Or place in the fridge for 3 hours or longer).

The very hardest part about this recipe is rolling the crust out large enough to fit in a half sheet pan. That and remembering what flours to buy, apparently. Trust me when I say that parchment paper is your friend.

How to Prevent a Soggy Pie Crust (Tomatoes are Juicy)

Ripe heirloom tomatoes are not only incredibly delicious, but they are notoriously juicy. There are a few things you can do to help ensure that your crust doesn’t get soggy.

• First of all, cut the tomatoes into approximately 1/3-1/2 inch slices and place in a single layer (ish) on a double layer of paper towels. Sprinkle with salt then add more paper towels on top. Let them sit and drain for at least an hour.
• Next, once the rolled-out crust comes out of the freezer, brush the entire crust with an egg wash.
• Then sprinkle on plenty of cheese as a base layer.
• Finally, try baking the gluten free pie in the lower portion of your oven.

Together, these tips will help prevent your gluten free pie crust from getting soggy.

How to Make Gluten Free Tomato Slab Pie

• 1 1/2 cups grated cheese (mozzarella, jack, pepper jack, fontina are all good here)
• 1/2 cup grated parmesan cheese or aged gouda
• 2 tablespoons butter
• 2 onions, thinly sliced
• 1/2 cup chopped parsley or basil or a combination
• 4 large cloves of garlic, minced
• 2 pints of heirloom cherry tomatoes – OR 6-7 large heirloom tomatoes, thickly sliced
• handful of basil (or cilantro) leaves, sliced
• 1 more egg…for the eggwash

1. Preheat the oven to 400°F.
2. Place a large sheet of parchment paper on your counter and dust lightly with sweet rice flour. Remove the disk from the freezer and place on the parchment. Dust with more rice paper and carefully roll out into a rectangle approximately one inch larger than your (half sheet) pan. Mine is 18×13.
3. Place the pan upside down on your dough, and quickly flip the dough over into the pan….you might want a friend to help with this part.
4. Tuck the edges under and press into the sides of the pan or crimp, if desired. Place in the freezer to chill for at least 30 minutes.
5. Melt the butter in a large skillet over medium heat. Add the onions and cook until soft and golden, about 15 minutes. Set aside to cool.
6. Take the crust out of the freezer and brush all over with a beaten egg. Top with the shredded cheese and cooked onions. Sprinkle on the parsley or basil and garlic and top with cherry tomatoes or sliced heirloom tomatoes.
7. Bake for 35-40 minutes, or until crust is golden brown and tomatoes are beginning to look caramelized. Let pie rest for about 10 minutes, then top with basil leaves. Serve warm or room temperature.

Once the dough is made and rolled out, it really is a piece of cake..er pie.. to put together. Happily it tastes equally good warm or room temperature and I think it would be perfect picnic or concert in the park fare.

Love pie? Me too! Here are a few more gluten free pie recipes to try!

• How To Make The Best Gluten Free Pie Crust
• Pear Pie with Gluten Free Pie Crust
• Gluten-Free French Apple Pie
• Chicken Pot Pie

If you make this recipe, or any of my others be sure to tag me on Instagram, and use the hashtags #agirldefloured #deflouredrecipes!

Gluten-Free Tomato Slab Pie

Feast your eyes on this beautiful gluten free Heirloom Tomato Slab Pie, a rustic tart made in a half sheet pan! This savory delight features a golden, flaky crust that cradles layers of gooey cheese and sweet, caramelized onions. Topping it all off are vibrant slices of heirloom tomatoes, their rich colors and juicy flavors taking center stage. Perfect for sharing, this slab pie is a celebration of summer’s best produce, melding creamy, tangy, and savory elements into each irresistible bite. Ideal for picnics, gatherings, or simply indulging in a slice of seasonal perfection.

5 from 1 vote

Print Recipe Pin Recipe

Prep Time 30 minutes mins

Cook Time 20 minutes mins

Total Time 50 minutes mins

Course Main Course

Cuisine American

Servings 12 servings

Calories 464 kcal

Equipment

• Food Processor
• Half Sheet Pan

Ingredients

 

US CustomaryMetric

 

1x2x3x

For the pie crust

• 1¼ cups tapioca flour
• 1 cup plus 2 tablespoons cornstarch
• ½ cup sweet rice flour plus more for dusting
• ¼ cup plus 2 tablespoons sorghum flour
• 2 teaspoons granulated sugar
• ½ teaspoon sea salt
• 2¼ teaspoons xanthan gum
• 1½ cups 3 sticks cold, unsalted butter, diced
• 4 extra large eggs

For the filling:

• 1½ cups grated cheese mozzarella, jack, pepper jack, fontina are all good here
• ½ cup grated parmesan cheese
• 2 tablespoons butter
• 2 onions thinly sliced
• ½ cup chopped parsley
• 4 large cloves of garlic minced
• 2 pints of heirloom cherry tomatoes or 6 large heirloom tomatoes
• handful of basil or cilantro leaves, sliced
• 1 more egg…for the eggwash

Instructions

 

• Place the tapioca, cornstarch, sweet rice flour, sorghum flour, sugar, salt, and xanthan gum in your food processor fitted with the steel blade attachment. Pulse to combine. Add butter and pulse until your mixture resembles coarse crumbs. Beat the eggs separately in a bowl. Pour through the hole in the top of the processor and pulse until the mixture just comes together in a ball. Flatten into a disk on a sheet of plastic wrap, seal and freeze for 30 minutes to an hour, or until firm. (Or place in the fridge for 3 hours or longer).
• Preheat the oven to 400°F.
• Place a large sheet of parchment paper on your counter and dust lightly with sweet rice flour. Remove the disk from the freezer and place on the parchment. Dust with more rice paper and carefully roll out into a rectangle approximately one inch larger than your (half sheet) pan. Mine is 18×13.
• Place the pan upside down on your dough, and quickly flip the dough over into the pan….you might want a friend to help with this part. Tuck the edges under and press into the sides of the pan or crimp, if desired. Place in the freezer to chill for at least 30 minutes.
• Melt the butter in a large skillet over medium heat. Add the onions and cook until soft and golden, about 15 minutes. Set aside to cool.
• Take the crust out of the freezer and brush all over with a beaten egg. Top with the shredded cheese and cooked onions. Sprinkle on the parsley or basil and garlic and top with cherry tomatoes or sliced heirloom tomatoes.
• Bake for 35-40 minutes, or until crust is golden brown and tomatoes are beginning to look caramelized. Let pie rest for about 10 minutes, then top with basil leaves. Serve warm or room temperature.

Nutrition

Serving: 1sliceCalories: 464kcalCarbohydrates: 35gProtein: 9gFat: 33gSaturated Fat: 20gPolyunsaturated Fat: 2gMonounsaturated Fat: 9gTrans Fat: 1gCholesterol: 152mgSodium: 514mgPotassium: 281mgFiber: 2gSugar: 4gVitamin A: 1641IUVitamin C: 23mgCalcium: 172mgIron: 1mg

Keyword Gluten Free Pie, Gluten Free Pie Crust, Gluten Free Tomato Pie, Gluten Free Tomato Slab Pie

Tried this recipe?Let us know how it was!

Thank you for helping support my small business! A Girl Defloured earns revenue in a few different ways; I have occasional sponsored post and I also earn an affiliate commission on the sales of products I link to— there are a few of those links in this post. The only items that I feature are those that I use on a regular basis and that I truly love. I earn a small commission on your purchase, but you don’t pay any more than retail price. This allows me to share my recipes with you!