In the bowl of a stand mixer, add the flour, sugar, cocoa, baking soda, baking powder, and salt. Mix them just until evenly combined.
In a small bowl, whisk together the milk and malt powder until completely combined.
Mixing on medium, slowly pour in the milk mixture until evenly combined. Mix in the eggs and oil, just until the mixture's smooth.
Mix in the sour cream and vanilla extract, just until the mixture's once again smooth.
Grease & flour 2-3 9" cake pans, depending on your desired thickness/number of layers. Pour the cake batter evenly into the prepared pans. Pat the pans down on a flat surface to remove any air bubbles. Bake the cakes at 350 for 20-25 minutes, or until a toothpick inserted in the center of each comes out clean.
Let the cakes rest in the pans for 10 minutes. Run a butter knife around the edges of the pan to ensure the cake has 'released'. Flip the cakes out over wired racks and let them cool completely.