Preheat the oven to 400 degrees F (200 degrees C). Place a drip pan on the lowest oven rack to catch pie juices.

Press pie crust into a 9-inch pie dish. Combine 3/4 cup sugar, 3/4 cup flour, 6 tablespoons butter, and nutmeg in a medium bowl until fluffy; set topping aside.

Add strawberries to a large bowl. Combine remaining 1/2 cup sugar, remaining 1/2 cup flour, and cornstarch together in a separate bowl; add to strawberries, stirring gently until coated, being careful not to crush berries.

Pour strawberries into prepared pie crust, mounding them in the middle as berries will sink as they bake. Cover strawberries with topping; top with about 15 pea-sized pieces of butter. Wrap edges of pie crust with foil to prevent burning.

Bake in the preheated oven for 20 minutes, then reduce heat to 375 degrees F (190 degrees C) and bake 40 minutes more. With 10 minutes left of baking, sprinkle a little extra sugar over crumb topping, then finish baking.