The malted flavor makes this a standout chocolate cake for a wedding buffet.
Preheat oven to 350 degrees. Coat two 8-cup panettone molds with cooking spray. Dust with cocoa powder, tapping out excess. Set aside.
Sift flour, cocoa, malted milk, baking powder, baking soda, and salt into a large bowl; set aside. Combine vanilla and buttermilk in a glass measuring cup; set aside.
Beat butter in the bowl of an electric mixer fitted with the paddle attachment until creamy. Add granulated sugar; beat until pale and fluffy. Beat in eggs, one at a time. Add flour and buttermilk mixtures in three alternating batches, beginning and ending with flour. Divide batter between pans; tap firmly to settle batter.