Preheat the oven to 350 F. In a large bowl, whisk together flour, sugar, cocoa powder, salt, and baking soda. Add in the eggs, melted butter and vanilla extract, and mix until smooth.
Pour the batter into a greased round 9-inch cake pan. Bake for 20-25 minutes. Let cool completely. Cut into a football shape. Decorate with icing in a football pattern.