In a large bowl, gently combine blackberries with sugar, lemon zest, lemon juice, vanilla and 2 tbsp. flour. Add additional flour if the mixture is very wet.
Gently unfold and lay out pie crust on a baking sheet lined with parchment paper.
Pour the blackberry mixture in the center of the unfolded pie crust leaving a 2-inch border. Fold up the uncovered border over the edge of the fruit and pinch into pleats.
Whisk egg and, using a pastry brush, brush the egg onto the crust and sprinkle with almonds and sugar.
Bake until juices are bubbling and the crust is golden, 35 to 40 minutes.
Remove from oven, let sit for 5-10 minutes, serve with a scoop of ice cream on top and enjoy!
Notes
You can also use frozen blackberries in this recipe. There is no need to thaw them first and no need to add any extra baking time.