In a bowl, combine 1 cup of all-purpose flour and salt.

Cut in butter until the mixture resembles coarse crumbs.

Stir in whipping cream.

Pat the dough into a greased 13x9x2 inch baking pan.

Combine the granulated sugar and remaining all-purpose flour and sprinkle over the crust.

Arrange fresh blackberries evenly over the crust.

For the topping, combine the granulated sugar and all-purpose flour in a separate bowl.

Stir in beaten large eggs, whipping cream, and vanilla extract.

Pour the topping mixture evenly over the blackberries.

Bake in a preheated oven at 375 degrees F (190 degrees C) for 40-45 minutes, or until lightly browned.

Let cool slightly before serving.

Serve hot or chilled.

Store any leftovers in the refrigerator.