Preheat your oven to 350 degrees F (175 degrees C). Grease your 9-inch cake pan generously with butter or non-stick spray.

In a medium saucepan over medium heat, melt the unsalted butter (1/2 cup) for the pecan topping. Stir in packed brown sugar (1 cup) until dissolved, then add salt (1/4 teaspoon) and heavy cream (1 tablespoon). Pour the mixture into the prepared cake pan and arrange pecan halves (1 1/2 cups) on top.

In a medium mixing bowl, whisk together all-purpose flour (1 1/2 cups), baking powder (1 1/2 teaspoons), baking soda (1/2 teaspoon), and salt (1/4 teaspoon). Set aside.

In a large mixing bowl, cream together softened butter (1/2 cup) and granulated sugar (3/4 cup) using an electric mixer until fluffy. Add eggs (2) one at a time, then add vanilla extract (1 teaspoon) and mix until combined.

With the mixer on low, alternate adding the dry ingredients and buttermilk (3/4 cup) to the butter mixture, starting and ending with the flour.

Spoon the batter over the pecan layer and spread evenly. Bake in the preheated oven for 35 to 40 minutes, or until a toothpick comes out clean.

Let the cake cool in the pan for 10 minutes before flipping it onto a serving plate. If any pecans stick, gently press them back into place.