Preheat your oven to 325°F. Grease an 8-inch square cake pan and set aside.

Combine the beer, milk, and Irish cream in a saucepan and heat just until body temperature.

In a small bowl, whisk together the flour and cocoa powder until evenly coloured and lump free.

In a stand mixer fitted with a whisk attachment or a bowl with a hand mixer, beat the egg whites and vinegar on high until you reach stiff peaks. If using a stand mixer, scrape the egg whites into another bowl and proceed. If using a hand mixer, use a second bowl to proceed.

Beat the egg yolks and sugar together until they are silky smooth and a lighter yellow. Beat in the butter until fully incorporated, then the flour and cocoa mixture until smooth. Pour in the beer mixture and the Jameson whiskey, and the extracts and beat that until totally smooth.

Now is where it's going to look like you're going wrong, but I promise you're not. whisk about 1/3 of the egg whites into the cake batter with enthusiasm. It'll look like you're deflating the egg whites, but it's okay. Now, take the remaining 2/3 of the whipped egg whites and fold them in just until the big clumps of egg white are broken up and you have what looks to be very loose batter with little egg white bubbles floating around in it. It looks like a hot mess, but it'll all work out in the oven.

Bake in your preheated oven for 50 minutes, or until the cake is set on top and still wiggly underneath, rather like a cheesecake should be. Let the cake cool at room temperature until you can comfortably handle the pan, then cover with plastic wrap and refrigerate until firm.

Slice into squares and serve garnished with Bailey's (or plain) whipped cream, a dusting of cocoa powder, and a drizzle of chocolate sauce.