First, preheat your oven to 350°F (175°C). This ensures a consistent baking temperature, allowing your pie to cook evenly.
Next, remove the pie crust from its packaging and lay it in your pie dish. Feel free to crimp the edges for a decorative touch! This crust will cradle all the deliciousness to come.
Pour the apple pie filling into a large bowl. Using a knife, coarsely chop the apples to create a rustic texture. This will add character to your filling.
Now, set aside 1/3 cup of the sweetened condensed milk. Pour the remaining condensed milk into the bowl with the apples. Mix everything together until smooth, ensuring each piece of apple is coated in that creamy goodness.
Pour the apple mixture into your prepared pie crust, using a spatula to smooth it into an even layer. This helps every slice maintain that perfect balance of crust and filling.
In a microwave-safe bowl, melt the unsalted butter until it's just melted. Allow it to cool slightly; hot butter can make your streusel greasy rather than crumbly.
In another bowl, whisk together the flour, light brown sugar, ground cinnamon, apple pie spice, and salt. This mixture will form the crumbly streusel topping that brings texture to your pie.
Drizzle the cooled melted butter into the dry mixture. Mix until everything is combined and forms small clumps. The streusel should be crumbly yet cohesive, ready to sprinkle over your pie.
Evenly sprinkle the streusel mixture over the apple filling. Be generous! This crunchy topping is what makes Apple Streusel Pie so irresistible.
Place your pie on a sheet pan and bake in the preheated oven for about 50 to 60 minutes, or until the filling is firm and the streusel is lightly browned. Keep an eye on it, as ovens vary!
Once baked, remove the pie from the oven and let it stand for 1 to 2 hours. This cooling time helps the filling set, allowing for clean slices when serving.
Finally, drizzle the remaining sweetened condensed milk over the top of your pie for an extra layer of indulgence. Cut into slices, serve warm or at room temperature, and enjoy!
