Step 1

Heat the oven to 350 degrees F. Spray an 8x8 pan with nonstick cooking spray. (Note: I often also like to line it with parchment paper before spraying it for super easy removal, but this is optional.)

Step 2

In one medium mixing bowl whisk together flour, sugar, baking powder, and salt.

Step 3

In a smaller mixing bowl whisk together the egg and vanilla until smooth. Add the milk, sour cream, and vegetable oil and mix again until smooth.

Step 4

Pour the wet ingredients over the dry ingredients and gently stir them together until no dry spots remain. Be careful not to overmix the batter - you'll know it's ready when it still looks slightly lumpy but all of the dry ingredients are mixed in.

Step 5

Pour the cake batter into the prepared pan.

Step 6

Bake until a tester inserted in the center comes out clean and the cake is golden on top, 30 to 33 minutes.

Step 7

Let the cake cool before slicing and serving. (Note: If adding frosting, be sure that the cake is completely cool before adding frosting.)