Instructions:

1. Prepare the Strawberry Topping: Preheat your oven to 350°F (175°C). In a medium bowl, combine the melted butter and brown sugar. Stir until well combined, then pour this mixture into the bottom of a 9-inch round or 9x9-inch square baking pan. Spread it evenly. Arrange the sliced strawberries on top of the butter-sugar mixture, covering the entire surface.

2. Prepare the Cake Batter: In a separate bowl, whisk together the flour, baking powder, and salt. Set aside. In a large mixing bowl, beat the softened butter and granulated sugar until light and fluffy. Add the egg and vanilla extract, mixing well after each addition. Alternate adding the dry ingredients and milk to the butter-sugar-egg mixture, beginning and ending with the dry ingredients. Mix until just combined after each addition.

3. Assemble and Bake: Carefully spoon the batter over the arranged strawberries, spreading it evenly. Bake in the preheated oven for 40 to 45 minutes, or until a toothpick inserted into the center comes out clean.

4. Cool and Invert: Allow the cake to cool in the pan for about 10 minutes. Run a knife around the edge to loosen it. Place a serving plate over the pan and carefully invert the cake onto the plate. Let it sit for a few minutes before removing the pan to set the topping.