Preheat oven to 350°F
Grease 3x 8-inch round cake pans with butter. Then line the bottoms with parchment paper.
Sift together flour, cocoa, baking soda, baking powder, salt, and cayenne pepper into a large bowl. Then whisk in the sugar.
In another bowl whisk the eggs. Then add the milk, oil, and vanilla. Whisk to combine.
Pour the wet ingredients into the bowl with the dry ingredients and whisk until smooth. Wiping down the sides of the bowl with a silicone spatula.
Add the 2 teaspoons of instant coffee in the boiling water and stir to dissolve. Pour the coffee into the cake batter, and mix well.
Pour equal amounts of the batter into the 3 cake pans (approximately 1 ¾ cups each).
Place cakes in the preheated oven and bake for 30-35 minutes or until a toothpick inserted into the centre comes out clean.
Let cool for 10 minutes, then remove from pans and let cool on a wire rack for at least an hour before frosting.