1. Preheat the Oven: Preheat your oven to 350°F (175°C). Grease a 9-inch round cake pan and line the bottom with parchment paper.
2. Prepare the Pecan Topping: In a small saucepan over medium heat, melt 1/2 cup of unsalted butter. Stir in the brown sugar until it’s well combined and begins to bubble. Remove from heat.
3. Pour the caramelized mixture into the bottom of the prepared cake pan. Sprinkle the pecan halves evenly over the caramel.
4. Prepare the Cake Batter: In a medium bowl, whisk together the flour, baking powder, and salt. Set it aside.
5. In a separate large bowl, cream together the softened butter and granulated sugar until light and fluffy.
6. Beat in the eggs, one at a time, ensuring each is fully incorporated before adding the next. Stir in the vanilla extract.
7. Gradually add the dry ingredients to the wet ingredients, alternating with the milk. Begin and end with the dry ingredients, mixing until just combined.
8. Assemble and Bake: Pour the cake batter over the pecan topping in the cake pan. Smooth the top with a spatula.
9. Place the cake pan in the preheated oven and bake for approximately 35-40 minutes, or until a toothpick inserted into the center comes out clean.
10. Cool and Invert: Remove the cake from the oven and allow it to cool in the pan for about 10 minutes. Then, run a knife around the edge of the pan to loosen the cake. Place a serving plate upside down over the top of the cake pan, and quickly invert the cake onto the plate. Carefully remove the cake pan, leaving the pecan topping on top.
11. Serve: Your Pecan Upside Down Cake is now ready to be served. Enjoy a slice of this delicious treat with a dollop of whipped cream or a scoop of vanilla ice cream.

This cake is a delightful blend of caramelized pecans and moist, tender cake. It’s perfect for dessert or a special occasion. Enjoy!