1-First Steps: Preheat and Prep: Begin by preheating your oven to 350°F (175°C). Prepare your workspace by peeling, coring, and slicing the 7 medium Gala apples evenly to ensure uniform cooking. In a large mixing bowl, toss the apple slices with 1 tablespoon lemon juice, 1/3 cup all-purpose flour, 1/2 cup granulated sugar, 1/4 cup packed light brown sugar, 1 1/2 teaspoons ground cinnamon, and 1/8 teaspoon salt to coat the fruit evenly and enhance the flavors.

2-Assembling the Pie: Fit the homemade pie crust into a 9-inch pie dish, pressing it to the sides and trimming the edges if necessary. Spread the apple mixture evenly into the pie crust, making sure not to overfill for even baking. In another bowl, combine 1/2 cup old-fashioned oats, 1/3 cup all-purpose flour, 2 tablespoons packed light brown sugar, 3 tablespoons melted unsalted butter, and 1/3 cup chopped pecans to create the streusel topping.
Use your fingers or a pastry cutter to blend until coarse crumbs form, then sprinkle this mixture generously over the apples. Place the pie on the center rack of the oven and bake for 50-60 minutes, or until the crust is golden and the filling bubbles. For dietary adaptations, consider using vegan butter or gluten-free flour in the streusel and ensure the pie crust meets your needs. Allow the pie to cool for at least 2 hours before serving to let the filling set, and pair it with extras like vanilla ice cream for a treat.