INGREDIENTS
Pie Dough:
1/3 cup
ice water, plus extra as needed
3 tbsp
sour cream
2 1/2 cups
all-purpose flour
1 tbsp
sugar
1 tsp
salt
16 tbsp
unsalted butter, cut into 1/4-inch pieces and frozen for 15 minutes
Filling:
3/4 cup
sugar, plus 1 teaspoon for topping
5 tbsp
cornstarch
1/4 tsp
salt
20 oz
blackberries
2 tbsp
lemon juice
2 tbsp
unsalted butter, cut into 1/2-inch pieces
1
large egg, lightly beaten