Preheat the oven to 400 °F. Drizzle a little olive oil in a 9″ springform pan and spread it evenly with your fingers. Line the bottom with a layer of parchment and add a little more olive oil to coat it, taking time to smooth any air bubbles. Sprinkle a couple of tablespoons sugar into the pan and shake to coat the bottom and sides. Dump out any excess sugar and set the pan aside.
Place the orange zest, orange juice, vanilla and eggs in the bowl of a stand mixer fitted with a whisk attachment. Beat the eggs until they become pale and thick. With the mixer running, slowly pour in the sugar and beat until the mixture is pale and glossy and runs off the whisk in thick ribbons.
Add the olive oil, flour, almond flour, baking powder, baking soda, and salt to the bowl and whisk until smooth. Whisk in the amaretto.
Pour the batter into the prepared pan, top decoratively with the pear and almond slices.
Put the pan in the oven and reduce the heat to 350 °F and bake for 40-50 minutes, or until a toothpick inserted in the middle comes out clean. Cool the cake in the pan for 15 minutes, then run a knife around the edge and release the sides from the pan and allow it to cool completely.
Store the cake tightly wrapped at room temp. This cake tastes even better the next day so make it ahead if possible! Dust with powdered sugar before serving.