Prep the pan and oven. Heat the oven to 350°F (175°C).
Grease a 9x13-inch pan and line the bottom with parchment for easy removal. Lightly flour the sides.
Whisk the dry ingredients. In a large bowl, whisk flour, sugar, cocoa, baking powder, baking soda, and salt until well combined and lump-free.
Mix the wet ingredients. In a second bowl, whisk eggs, milk, oil, and vanilla until smooth. Pour wet into dry and stir just until combined.
Add the hot coffee. Slowly pour in the hot coffee while mixing on low.
The batter will be thin—that’s normal. It makes a moist cake.
Bake. Pour into the pan and bake 28–34 minutes, or until a toothpick comes out clean with a few moist crumbs. Cool in the pan 15 minutes, then turn onto a rack to cool completely.
Make the buttercream. Beat butter until creamy.
Add powdered sugar, cocoa, salt, vanilla, and 2 tablespoons cream. Beat on low, then increase speed to fluffy. Add more cream a little at a time until smooth and spreadable.
Shape the football (sheet-cake method). Place the cooled cake on a large board.
With a toothpick, outline a large football shape—an oval with pointed ends—leaving a little border around the edges. Use a serrated knife to trim along the outline. Set aside the scraps (snacks!).
Crumb coat. Spread a thin layer of chocolate frosting over the entire cake to lock in crumbs.
Chill 20–30 minutes to set.
Final frost. Apply a thicker, even layer of chocolate buttercream. Smooth with an offset spatula, following the football shape. Don’t worry about perfection—texture reads as “leather.”
Add the white details. Fill a piping bag with white frosting.
Pipe two short stripes near each pointed end of the football. In the center, pipe one long line lengthwise. Add 5–7 short crosswise laces over the center line.
For clean lines, hold the bag slightly above the surface and let the icing fall into place.
Optional field effect. If you want a “field,” spread a thin layer of white or chocolate frosting on the board around the cake. Press green coconut or sprinkles into it to look like turf. You can also pipe yard markers or team initials.
Chill briefly, then serve. Refrigerate the cake 15 minutes to set the design.
Slice with a hot, dry knife for clean pieces.