Preheat the oven to 350 F. grease and flour an 18x13” baking sheet. (half slab size)
In a medium bowl, whisk together the flour, baking powder, and salt; set aside.
1 ½ cups flour, 1 teaspoon baking powder, ¼ teaspoon salt
In a separate bowl, cream together the butter and sugar until light and fluffy. Add the eggs and vanilla and mix well.
½ cup butter, 1 cup sugar, 2 large eggs, 1 teaspoon vanilla extract
Add the dry ingredients to the wet ingredients, then stir until just combined. Stir in the sour cream until no streaks remain.
½ cup sour cream
Spread the cake batter evenly into the prepared pan, using an offset spatula to get an even thickness.
Bake in the preheated oven for 16-20 minutes, or until a toothpick inserted into the center comes out clean.
Allow to cool completely, then use a tree shaped cookie cutter to cut out the cake. Be sure to cut as closely together as possible to ensure maximum usage of the cake.