Have all the ingredients at room temperature.

Position a rack in the lower third of an oven and preheat to 350°F. Grease and flour the wells of a railway cake pan and dust with Wondra® flour.

Sift the flour, sugar, baking powder, baking soda and salt into the bowl of an electric mixer. In a separate bowl, whisk together the melted butter, sour cream, eggs and vanilla until combined. Fit the mixer with the flat beater. Add the butter mixture to the flour mixture and beat on the lowest speed until the dry ingredients are moistened, 15 to 20 seconds. Stop the mixer and scrape down the sides of the bowl. Increase the speed to medium and beat for 30 seconds.

Divide the batter in half and set half of it aside. Spoon the remaining batter evenly among the prepared wells. Tap the pan firmly on the countertop to release any air bubbles. To ensure good details on the cakes, spread the batter so it reaches the top edges of each well and is slightly lower in the center of the well. Bake until a toothpick inserted into the center of a cake comes out clean, 18 to 22 minutes.

Transfer the pan to a wire rack and let cool for 10 minutes, then invert the cakes onto the rack and let cool for at least 1 hour before decorating or serving.

Wash and thoroughly dry the pan. Grease and flour the wells and repeat with the remaining batter. Makes 18 cakes.