Prepare two 8-inch cake tins or three 6-inch cake tins (used in recipe shown) by greasing, flour dusting and lining bottoms with parchment paper, set aside
In a large bowl fitted with a stand mixer or hand mixer cream butter for 3-5 minutes until light and fluffy. Add in brown sugar and beat for an additional two minutes. In a steady stream add in vanilla extract and maple syrup until incorporated. Crack in one egg at a time, beating well after each addition.
Dissolve instant coffee granules in boiling water and beat into butter/ sugar mixture. In a large bowl combine all dry ingredients (flour + baking powder + salt) and mix well. Add half of this dry mixture into wet sugar mixture. Alternating between milk and dry ingredients until everything is mixed and incorporated, *do not over mix. Remove from beater and gently fold in walnuts. Pour evenly into cake tins and bake for 20-25 minutes until a toothpick is removed clean. Let cool for twenty minutes. Ring a knife around sides of cake tins and transfer to cooling racks for an additional thirty minutes until cooled. Trip dome tops if needed.
for buttercream
In a large bowl fitted with a hand or stand mixer beat butter, vanilla extract and salt until light and fluffy. In a small bowl dissolve coffee granules with boiling water. Add coffee granule mixture and milk to butter and half of powdered sugar and beat well. Scrape down sides of bowl and add in the rest of the powdered sugar and beat until light and fluffy.