Pre-heat the oven to 350. Take two 9 inch round cake pans and line them with parchment paper, then spray them liberally with cooking spray. In a bowl whisk together the flour, cocoa powder, baking soda, baking powder and salt. Set the bowl aside. In another microwave safe bowl combine the bakers chocolate and almond milk. Microwave it for 30 seconds to a minute, until it is melted. Stir it together thoroughly into a smooth ganache and set it aside.

In the bowl of a stand mixer fitted with the paddle attachment, cream the butter and sugar together until it is completely fluffy and soft. Add the eggs and egg yolks one at a time, letting each one get stirred in before the next one gets added. Then add the white vinegar and let it get stirred in completely.

Turn the speed to low and slowly add 1/3 of the dry ingredients, followed by half of the Guinness. Then add the next third of the dry ingredients followed by the rest of the Guinness. Lastly, pour the remaining dry ingredients until everything is just combined into a batter. Switch to a rubber spatula and gently fold in the chocolate ganache to make it super rich.

Evenly divide the batter among the two prepared cake pans and smooth out the batter in each pan to be nice and even. Let them bake in the oven for about 30 minutes, until they are completely done and a toothpick inserted in the center comes out clean. Take them out and let them cool for at least 30 minutes, then carefully turn them out onto individual plates to finish cooling completely for another 20 to 30 minutes. The cake layers can be made ahead to this point if desired. Just cover them and refrigerate them up to 24 hours.

While the layers cool, or the next day if making ahead, prepare the buttercream frosting. You will need to make sure your stand mixer bowl and paddle attachment are clean from making the cake batter. Fill a small saucepan with water and bring it to a gentle simmer over medium heat. Combine the chocolate, sugar, almond milk and Guinness in a heatproof bowl and set it over the simmering water without letting the bottom touch the water. Let the chocolate melt in the double boiler while stirring with a heatproof spoon or spatula until the mixture it smooth and shiny. Take the bowl off of the heat and set it aside.

In the stand mixer bowl thoroughly beat the butter until it is fluffy and creamy with the paddle attachment. Add the pinch of salt and the shiny ganache to let them get completely stirred in. Then slowly add the powdered sugar on low speed until a fluffy, luscious frosting forms.

Line a pretty cake plate with parchment paper to keep it clean while frosting. Carefully add the first cake layer and generously frost the top of it. Then put the second layer on top of the frosting and completely frost the top and sides of the cake with an offset spatula to make it smooth. Carefully slide the parchment paper out from under the cake, then slice the cake and serve immediately!