In a large bowl, whisk together the flours, cocoa, sugars, baking powder, baking soda, and salt. In a medium bowl, whisk together the yogurt and milk. Whisk in the eggs one at a time, then whisk in the olive oil, vanilla, and maple syrup if using. Slowly add the wet ingredients to the dry using a wooden spoon or rubber spatula. Then add the coffee and whisk lightly or stir just to combine, scraping the bottom of the bowl with a rubber spatula.

In a large bowl, whip the butter with a mixer until it is smooth and fluffy. Add the melted chocolate and the powdered sugar and whip to combine, then add the milk (more if needed) to make a smooth, fluffy frosting. Frost the top and sides of the cake with the frosting.