1. Preheat the Oven:
Preheat your oven to 350°F (175°C). Grease a 9-inch round cake pan and set it aside.
2. Prepare the Topping:
In a saucepan, melt the 1/4 cup of butter over medium heat. Add the brown sugar and stir until it dissolves and begins to bubble. Remove it from the heat and pour it into the greased cake pan, spreading it evenly.
Arrange the sliced apples on top of the caramelized sugar mixture. Sprinkle with the 1/2 teaspoon of ground cinnamon.
3. Prepare the Cake Batter:
In a separate bowl, whisk together the flour, baking powder, salt, 1/2 teaspoon of cinnamon, and nutmeg.
In another large mixing bowl, cream the 1/2 cup of softened butter and granulated sugar until light and fluffy. Beat in the eggs one at a time, followed by the vanilla extract.
Add the dry ingredient mixture to the wet ingredients in three parts, alternating with the milk. Begin and end with the dry ingredients. Mix until just combined.
4. Assemble and Bake:
Pour the cake batter over the arranged apple slices in the cake pan. Spread it out evenly.
Bake in the preheated oven for 30-40 minutes, or until a toothpick inserted into the center of the cake comes out clean.
5. Cool and Invert:
Allow the cake to cool for about 10 minutes in the pan. Then, run a knife along the edges to loosen it. Place a serving plate upside down on top of the cake pan and quickly flip it over. The cake should release onto the plate with the apples on top.
6. Serve:
Serve your apple upside-down cake warm or at room temperature. You can top it with a dollop of whipped cream or a scoop of vanilla ice cream for an extra treat.
Enjoy this delicious and comforting dessert!