Step 1

Preheat the oven to 350°F (175°C). Grease a 9x9-inch baking dish thoroughly with butter or nonstick spray and set aside.

Step 2

In a large mixing bowl, combine 1 cup of granulated sugar with the melted butter. Mix using a hand mixer or whisk for approximately 1 minute, or until the mixture appears smooth and slightly airy.

Step 3

Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract and mix until fully incorporated.

Step 4

In a separate bowl, sift together the cake flour, baking powder, and salt. Gradually add the dry mixture to the wet ingredients, stirring just until combined. Avoid overmixing.

Step 5

Gently fold in the sour cream using a spatula or wooden spoon until the batter is smooth and evenly mixed. The batter will be thick.

Step 6

Pour the batter into the prepared baking dish, smoothing the top evenly. Sprinkle the remaining 2 tablespoons of granulated sugar evenly over the surface of the batter.

Step 7

Bake in the preheated oven for 30 to 35 minutes, or until a toothpick inserted into the center comes out clean or with only a few moist crumbs. Remove from oven and allow the cake to cool in the pan before slicing and serving.