Chill a martini or coupe glass in the fridge or freezer so the cocktail stays cold and velvety.
Brew a shot of fresh espresso (or strong coffee) and let it cool slightly so it doesn't melt the ice too quickly.
Fill a cocktail shaker halfway with ice cubes.
Add the vodka, coffee liqueur, Irish cream, cooled espresso, and vanilla extract to the shaker. Add a small splash of amaretto if you want a nutty twist.
Shake hard for 15–20 seconds, until the outside of the shaker feels frosty and a nice foam has formed inside.
Double strain the mixture through a fine strainer into the chilled martini glass to catch any ice shards and keep the texture silky.
Slowly pour the heavy cream or cream liqueur over the top, using the back of a spoon if you'd like to float it in a soft layer.
Dust the top with cocoa powder or add a few chocolate shavings. If desired, finish with a small swirl of whipped cream for an extra tiramisu vibe.
Serve immediately while the foam is fresh and the coffee aroma is at its strongest.