Preheat oven to 350 degrees F. Prepare three 9-inch round cake pans with non-stick spray and/or parchment.
In the bowl of stand mixer with whisk attachment, add the granulated sugar and eggs and beat on high for 2-3 minutes.
Meanwhile, combine the hot water, cocoa powder, instant coffee, and salt. With mixer on lowest setting, add to sugar mixture.
With mixer still on low slowly add in flour, baking soda, and baking powder. Let mix to incorporate.
Add in oil, buttermillk, and vanilla extract. Scrape down sides and bottom of bowl as needed. Do not overmix.
Evenly pour batter into prepared pans and bake for 22 to 25 minutes, or until an inserted toothpick is removed clean.
Let cakes cool in pans for 10 minutes, then invert onto a wire rack. Let cakes cool to room temperature or place in fridge until ready to assemble.
KAHLUA WHIPPED CREAM
Place a clean stand mixer bowl with whisk attachment in the fridge for 15 minutes.
Remove bowl from fridge and place on mixer. Add cream and whip on high until soft peaks form.
Reduce mixer speed to low and slowly add in the confectioners' sugar, Irish Cream, Kahlua, and cornstarch.
Once everything is incorporated, turn mixer back to high and whip until stiff peaks form. Transfer to fridge until ready to assemble.
In a medium microwave-safe bowl, combine chocolate chips and heavy cream. Microwave on high for 15 seconds at a time, whisking together with a fork after each interval. Once the chocolate has melted into a shiny, smooth sauce (about 45 seconds total) transfer to the fridge to cool for 15 minutes.
Place the cool layer of cake on serving platter. Spread the top with 1/3 of the whipped cream. (If you want to pipe out the rope pattern, place whipped cream in a large pastry bag fitted with a 2C tip. Pipe circles on that are slightly overlapping around the cake.)
Drizzle 1/3 of the cooled ganache over the whipped cream. Sprinkle 1/3 of the chopped cookies. Add next layer of cake and repeat. Store in fridge until ready to serve.