Preheat your oven to 350°F. Grease a 9-inch round cake pan well and line the bottom with parchment paper.

For the pecan topping, melt 4 tablespoons of unsalted butter in a small saucepan with ½ cup packed light brown sugar and 2 tablespoons of maple syrup (or honey). Bring the mixture to a gentle bubble and let it cook for about 2 minutes until smooth and glossy.

Pour the caramel pecan topping evenly into the prepared pan and arrange 1 cup of pecan halves evenly over the top.

In a bowl, whisk together 1½ cups all-purpose flour, 1½ teaspoons baking powder, ¼ teaspoon baking soda, and ¼ teaspoon salt.

In a separate bowl, cream ½ cup softened unsalted butter with ¾ cup granulated sugar until light and fluffy. Add 2 large eggs one at a time, followed by 1 teaspoon vanilla extract.

Combine ½ cup sour cream (or plain yogurt) with ¼ cup milk, then gradually fold this mixture into the creamed butter mixture, alternating with the dry ingredients until you have a smooth, thick batter.

Spread the cake batter evenly over the pecan-caramel layer in the pan, ensuring not to disturb the arranged nuts.

Bake the cake for 30-35 minutes or until a toothpick inserted in the center comes out clean.

Allow the cake to cool in the pan for about 10 minutes. Then, place a serving plate over the cake pan and quickly flip it over. Let the pan remain in place for a minute so gravity helps the caramel drizzle over the cake, then carefully lift off the pan.

If any pecans stick to the pan, simply place them back on the cake before serving.