I'm using the same cake mix that I used for my dad's birthday mini cakes, and the coffee ice cream recipe that I used when we had a big Christmas brunch - the only exception is that I added 4 Tbsp of bourbon to the ice cream after warming it (during the last step of straining the mixture)!
I baked the cake in little 6" round pans (baked for 33-39 minutes, just using a toothpick to test the middle to be sure it comes out dry), and leveled off the top of the cake layers to be sure they were completely flat. Then I used the same pan lined with plastic wrap - plastic wrap doesn't stick to metal so it works perfectly for this! - and poured the finished ice cream into that to create a middle layer. I let it set for 12 hours, placed the ice cream tin in a bowl of water for less than a minute just to loosen it a tiny bit, and the pulled on the plastic and it came out in one piece! I placed it on one of the cake layers, and put the other layer on top of that, and immediately wrapped it back in plastic and placed it in the fridge for another few hours.
If I were a perfectionist, I'd carve down the outside of the ice cream since it's slightly larger than the cake. Cake pulls away from the edge when it's baking but obviously freezing ice cream does no such thing! However, I'm not a perfectionist so we had a slightly lopsided cake - perfectly edible and acceptable!
Meanwhile, I created chocolate whipped cream (I only had 1/2 C heavy cream left over from the ice cream mixture) using 1/2 Tbsp unsweetened cocoa powder, 2 tsp sugar, and 1 Tbsp cream to make a paste. Then I combined it with the remaining cream and let it sit while I went to work! This "incubation period" creates a richer flavor. I then used my beloved Kitchenaid mixer to whip it up and frost the cake!
I could've used a bit more whipping cream but I got it mostly covered! I then melted a little bit of dark chocolate for 30 seconds in the microwave in a baggie, snipped off the corner, and wrote her name on top. Turned out cute and tasty!
Happy birthday, Jamie!