Gluten-Free Tomato Slab Pie

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.
Jump to RecipeRecipe card updated 3/13/23
Unlike 90% 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
- 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 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
- 2 tablespoons butter
- 2 onions, thinly sliced
- 1/2 cup chopped parsley
- 4 large cloves of garlic, minced
- 2 pints of heirloom cherry tomatoes
- handful of basil (or cilantro) leaves, sliced
- 1 more egg…for the eggwash
- Preheat the oven to 450 degrees.
- 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. Place in the freezer.
- Melt the butter in a large skillet over medium heat. Add the onions and cook until soft and golden, about 15 minutes. Set aside.
- Take the crust out of the freezer and top with the shredded cheese and cooked onions. Sprinkle on the parsley and garlic and stud it all over with the cherry tomatoes. Beat the egg with a splash of water and brush all over the edges of the crust.
- Bake for 15-20 minutes, or until crust is golden brown and tomatoes are beginning to burst. 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
Equipment
- Half Sheet Pan
Ingredients
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
- 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 450 degrees.
- 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. Place in the freezer.
- Melt the butter in a large skillet over medium heat. Add the onions and cook until soft and golden, about 15 minutes. Set aside.
- Take the crust out of the freezer and top with the shredded cheese and cooked onions. Sprinkle on the parsley and garlic and stud it all over with the cherry tomatoes. Beat the egg with a splash of water and brush all over the edges of the crust.
- Bake for 15-20 minutes, or until crust is golden brown and tomatoes are beginning to burst. Let pie rest for about 10 minutes, then top with basil leaves. Serve warm or room temperature.
Thank you for doing your recipes
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Thanks for reading my blog!! 🙂
Totally inspirational for the gobs of cherry tomatoes coming off our plants. Luckily I have a frozen pie dough from earlier this month I just have to remember to take out and defrost.
Just need to get some non-dairy “cheese” that will melt in a half way decent way.
Thanks!
I had the exact same reaction when I saw PW’s post that day! I am still to inexperienced at GF baking to know which crust recipe to use. I have had so many baking failures I’m almost afraid to try again. But I want this badly, so will try again. As soon as I replenish my flour supply. I am completely out of all the basic flours and starches.
Hi Alison! I’m out of sorghum and sweet rice flour. Could I just use all purpose flour?
Gluten-free all purpose flour? This recipe is formulated to be a much lighter pastry blend than standard gluten-free flour blends. However if your flour blend is a higher percentage of starch, you can give it a try. 🙂
Hi Alison! I made this for dinner tonight. It was amazing! I had to do a couple of substitutes since I used all my sorghum and sweet rice flours to make your all purpose flour (which is amazing as well). I had to call my friend over to try some too. I just had to share. It tastes like a pizza I would buy in a gourmet pizza parlor. I also made your stone fruit crisp for desert. Amazing!
I love your recipe. I will surely try it.
This pie is different and looking beautiful..
I just recently made this pie for the second time, and it’s great! But, really, that pastry recipe is the star!! Easy to make, makes a ton, (I made a slab pie that took up 80% of my half-sheet pan, and froze the other half), and is rich and flaky. For Labor Day, my sister thawed the pastry and made an excellent free form plum tart! Our Mom isn’t GF and is super picky and she loved it. Thanks, I will always keep some in my freezer!
That is such a huge compliment — glad you love the slab pie and that plum tart sounds amazing too!