Crust and Topping
3 cups all-purpose flour
1 1/2 cups sugar
1/4 tsp salt
1 1/2 cups (3 sticks) unsalted butter, chilled
4 large eggs
2 cups sugar
1 cup sour cream
3/4 cup flour
zest of 1/2 lemon
1 tsp almond extract
2 (16-oz) packages frozen blackberries, thawed and drained
To make the crust and topping, preheat the oven to 350 degrees. Grease a 9×13 inch baking pan.
Combine the flour, sugar, and salt in the bowl of a food processor. Pulse a few times to mix. Cut the butter into 1/2-inch cubes, and add to the flour mixture. Process until the butter is evenly distributed but the mixture is still crumbly, 30-60 seconds.
Reserve 1 1/2 cups of the mixture to use as the topping. Press the remaining mixture into the bottom of the pan, and bake 12-15 minutes. Cool for at least 10 minutes.
To make the filling, whisk the eggs in a large bowl, then add the sugar, sour cream, flour, salt, lemon zest, and almond extract. Gently fold in the berries and spoon the mixture over the crust. Sprinkle the remaining flour mixture evenly over the filling, and bake 45 to 55 minutes.
Cool at least 1 hour before cutting into bars, or scoop out of the pan to serve cobbler-style.