For Crust

1. Preheat oven to 350 degrees.
2. Combine the flour, almond flour, sugar, cornstarch and salt in the bowl of a stand mixer fitted with the paddle attachment. Mix until combined, about 10 seconds.
3. Add the melted butter and mix until incorporated. Add the poppy seeds and stir in. Mixture will be dry but should stick together when pressed with your hands.
4. Press shortbread mixture into the bottom and up sides of a 9 inch fluted tart pan with removable bottom. Set tart pan on a cookie sheet.
5. Bake for 13-15 minutes until crust is slightly golden brown. Do not over bake.
6. Remove from the oven and set aside to cool slightly.
7. Lower the oven temperature to 350 degrees.

For Lemon Curd Filling

1. Place the cubed butter and lemon zest in a large bowl.
2. Place a medium saucepan filled with two inches of water over medium low heat. In a medium bowl that serves as a double boiler, whisk together sugar, eggs, egg yolks and salt to combined. Slowly add the lemon juice and stir to incorporate.
3. Place the bowl over the pot with water and heat the curd over medium low heat, stirring often until the mixture thickens and coats the back of a spoon. Be sure to stir the curd evenly as it cooks, scraping the bottom and sides of the bowl as you go. The curd is done when the mixture is thick and the temperature measures 165 degrees using an instant read thermometer.
4. Remove the curd from the heat and pour it through a fine mesh strainer into the bowl with the butter and lemon zest.
5. Whisk to combine well, stirring until all of the butter is melted and the curd is smooth.
6. Pour the curd into the prepare tart crust and bake for an additional 15 minutes. Be sure the oven temperature was lowered to 325 degrees. The center should not be liquid but set with a slight jiggle when you wobble the pan. Do not over bake.
7. Remove from oven and cool on cooling rack until room temperature.
8. Place tart in the refrigerator for 4 hours or overnight.
9. Slice and serve cold. Dust with confectioner’s sugar if desired.