Preheat your oven to 350°F (175°C). Prepare a 9-inch round cake pan by greasing it with butter and dusting it with flour.

In a small saucepan, melt the butter over medium heat. Stir in the brown sugar and cinnamon until the sugar is dissolved. Pour the mixture into the prepared cake pan and spread evenly.

Place the apple slices over the caramel mixture in a circular pattern, overlapping them slightly to cover the entire surface.

In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.

In a large mixing bowl, use an electric mixer to cream the butter and granulated sugar until light and fluffy. This should take about 3 minutes.

Beat in the eggs one at a time, ensuring each is fully incorporated before adding the next. Mix in the vanilla extract.

Gradually add the dry ingredients to the wet mixture, alternating with the milk, beginning and ending with the flour mixture. Mix until just combined.

Gently pour the batter over the apples in the cake pan, smoothing the top with a spatula.

Bake in the preheated oven for 45-50 minutes, or until a toothpick inserted into the center comes out clean.

Allow the cake to cool in the pan for 10 minutes. Run a knife around the edges to loosen, then carefully invert it onto a serving platter.

Serve warm, perhaps with vanilla ice cream or whipped cream. Enjoy the rich, caramelized apple topping and moist cake.

Store any leftovers in an airtight container at room temperature for up to 2 days, or in the refrigerator for up to 5 days.