Directions:
Preheat your oven to 325°F. Grease a 9-inch round cake pan.
In a small saucepan, melt the butter over medium heat.
Stir in the brown sugar and heavy cream. Bring to a simmer and cook for about 3 minutes, stirring occasionally, until the mixture thickens slightly.
Remove from heat and stir in vanilla extract.
Pour the mixture evenly into the prepared cake pan. Sprinkle the pecans over the syrup, evenly covering the base of the pan.
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.
In a large bowl, cream together the softened butter and granulated sugar until light and fluffy (about 3 minutes).
Add the eggs, one at a time, beating well after each addition. Mix in the vanilla extract.
Gradually add the dry ingredients to the wet mixture, alternating with the buttermilk and sour cream. Start and finish with the dry ingredients, mixing until just combined.
Gently pour the batter over the pecan topping in the pan, spreading it evenly with an offset spatula or butter knife. Place cake pan on a cookie sheet in case any of the syrup bubbles over when baking.
Bake in the preheated oven for 35–40 minutes, or until a toothpick inserted into the center of the cake comes out clean. Start checking at 30 minutes.
Allow the cake to cool in the pan for 5 minutes before carefully inverting onto a serving plate.
Let the cake cool slightly before slicing. The caramelized pecans will be beautifully sticky, and the cake will be soft and moist.