Preheat oven to 350°F (175°C) and prepare two 8-inch round cake pans by greasing and flouring them. In a large bowl, whisk together the dry ingredients; in another, cream butter with sugar, then beat in eggs and vanilla, gradually adding dry ingredients alternating with milk until just combined.

Divide the batter evenly into the prepared pans and bake for 25-30 minutes, or until a toothpick inserted comes out clean. Let cakes cool in pans for 10 minutes before transferring to a wire rack to cool completely.

For the frosting, beat softened butter until creamy in a large bowl, then gradually add powdered sugar, mixing until smooth. Beat in milk and vanilla extract until the frosting is light and fluffy.

Level the cooled cake layers if needed, then place one layer on a serving plate, spread with white frosting, and top with the second layer, covering the entire cake with white frosting.

Reserve a small amount of white frosting, then tint the rest red with gel food coloring; pipe or spread red frosting on the top half of the cake for Santa's hat, using reserved white for the brim and pom-pom, and white sprinkles or pearls for Santa's beard and mustache.

Place red candies or berries to create Santa's nose, and use chocolate chips or edible eyes for Santa's eyes.

Chill the decorated cake for at least 30 minutes to allow the frosting to set before slicing and serving.