Step 1: Preheat your oven to 375°F (190°C). Lightly grease a 9-inch pie dish or an 8x8 inch baking dish.
Step 2: Prepare the apple filling. In a large bowl, combine the sliced apples, granulated sugar, 2 tablespoons all-purpose flour, 1 teaspoon ground cinnamon, nutmeg (if using), and lemon juice. Toss gently until the apples are evenly coated.
Step 3: Pour the apple mixture into the prepared pie or baking dish, spreading it out evenly.
Step 4: Prepare the crumb topping. In a separate medium bowl, whisk together 1 cup all-purpose flour, brown sugar, rolled oats, 1/2 teaspoon ground cinnamon, and salt.
Step 5: Add the cold, cubed butter to the dry ingredients. Using a pastry blender, your fingertips, or two knives, cut the butter into the mixture until coarse crumbs form. You want some pea-sized pieces of butter remaining.
Step 6: Sprinkle the crumb topping evenly over the apple filling in the baking dish, ensuring the apples are well covered.
Step 7: Bake for 45-55 minutes, or until the topping is golden brown and the apple filling is bubbly and tender when pierced with a fork. If the topping starts to brown too quickly, you can loosely cover it with aluminum foil.
Step 8: Remove the Hillbilly Pie from the oven and let it cool on a wire rack for at least 15-20 minutes before serving. This allows the filling to set slightly.
Step 9: Serve warm with a scoop of vanilla ice cream, whipped cream, or a drizzle of caramel sauce for an extra treat. Enjoy your comforting Hillbilly Pie Poor Mans Pie!