Dark Chocolate Guinness Cake with Bailey's Buttercream

Preheat oven to 350 In a small saucepan, heat 1 1/2sticks of butter until just melted, then whisk together with Guinness, vanilla and cocoa. while Guinness mixture is cooling, grease and line the bottoms of 2 8" cake pans with parchment paper. Whisk together sugar, flour and baking soda in a large bowl. Pour Guinness mixture into dry ingredients, then whisk in the eggs. When batter is shiny and smooth, pour it into the prepared cake pans. Bake 30-35 minutes until a skewer comes out clean. Cool completely in pans. For buttercream: In a stand mixer, whip softened butter until fluffy. Add powdered sugar on low speed, then increase to medium high and drizzle in just enough Baileys to get the buttercream loose and fluffy. Whip frosting 5-10 minutes, scraping occasionally. to assemble cake: Run a knife around the edge of cake pans to loosen and turn out. Level layers with a serrated knife. Spread about 1/3 of buttercream on bottom cake layer. Top with 2nd layer. Thinly spread another 1/3 over the top and sides to make a crumb coat. Refrigerate to set (30 minutes or overnight) Once the crumb coat is firm to the touch, add the remainder of the frosting on top first, then sides.