Preheat your oven to 350°F (175°C). Prepare a 10-inch round cake pan by lining the bottom with a parchment paper circle. Generously coat the inside with non-stick spray or softened butter, and set aside.
Place the corn syrup, brown sugar, unsalted butter, and salt into a shallow pan or skillet over medium heat. Stir continuously until the mixture reaches a boil, then remove from the heat source.
Stir the pecans into the hot mixture, ensuring each piece is fully coated. Pour this mixture into the prepared cake pan, spreading it evenly across the bottom. Chill in the refrigerator while preparing the cake batter.
In a mixing bowl, combine the granulated sugar and eggs. Using a hand mixer (or whisk by hand), beat for 3–5 minutes until the mixture becomes pale and increases in volume.
Stir in the sour cream, cooled melted butter, whole milk, and vanilla extract. Mix until smooth and well incorporated.
In a separate bowl, whisk together the flour, baking powder, baking soda, and salt. Gradually fold the dry ingredients into the wet mixture. Mix only until combined—small lumps in the batter are expected and will contribute to a lighter texture.
Retrieve the chilled pecan layer from the fridge. Gently pour the prepared cake batter over it, smoothing the top with a spatula to create an even layer.
Bake in the center of the oven for 30–35 minutes, or until a toothpick inserted in the center comes out clean with just a few moist crumbs attached. The surface should appear golden brown and begin to pull away from the pan edges.
Once removed from the oven, immediately run a knife around the inner edge of the pan to loosen the sides. Let the cake rest for 8–10 minutes.
Position a serving plate on top of the cake pan. Holding both firmly, flip the cake pan and plate together in one swift motion. Carefully lift the pan away. If any pecans remain stuck, gently scrape them out and place back atop the cake.
Allow the cake to cool entirely before slicing into 10 equal portions for serving.