Apple Layer

1. Preheat the oven. Heat the oven to 350°F.
2. Prep the apples. Meanwhile, peel and core the apples. Slice the apples into thin wedges.
3. Prepare the pan and add the apples. Put the 1/4 cup of butter in a 9-inch square pan. Put it in the oven until the butter has melted. Remove the pan from the oven and sprinkle the butter with 1/2 cup of brown sugar. Arrange apple slices evenly over the butter and brown sugar layer.

Cake Layer

1. Make the batter. Combine the 2 cups of flour, 1 cup of granulated sugar, 1 tablespoon of baking powder, 1 teaspoon of salt, 5 tablespoons of softened butter, 1 cup of milk, and the egg in a large mixing bowl. Beat on low speed with an electric mixer until combined. Increase to medium speed and beat for about 2 minutes longer. Scrape the sides of the bowl occasionally. Spoon the batter evenly over the apples and then gently spread to cover.

Top and Bake

1. Make the streusel topping. In a medium bowl, combine 1/2 cup of brown sugar with the pecans, 1/4 cup of flour, and 1/2 teaspoon of cinnamon. Mix the 3 tablespoons of softened butter with a fork or your fingers until crumbs form. Sprinkle the streusel mixture evenly over the top of the batter.
2. Bake the cake. Bake the apple upside-down cake in the preheated oven for about 45 to 50 minutes, or until a wooden toothpick or a cake tester inserted in the center comes out clean.
   Invert and serve. Immediately invert the cake onto a large plate, platter, or pan and let stand for a minute. Remove the baking pan. If any apples stick to the baking pan, scrape them out onto the cake.