Step 1

In a small bowl, stir together espresso, hot water, and sugar. Stir to combine; set aside.

Step 2

In the bottom of a 3 1/2-quart trifle dish, place an even layer of cake cubes, cutting pieces to fit as necessary. Using a pastry brush, brush the cake cubes with 1/3 of the reserved espresso mixture to moisten. Using an offset spatula, spread 3 cups of vanilla ice cream on top of the cake layer. Repeat process and top with a layer of cake cubes brushed with remaining espresso mixture.

Step 3

Cover trifle with plastic wrap and transfer to freezer; freeze until ice cream is set, about 1 hour and up to 1 week.

Step 4

When ready to serve, remove trifle from the freezer 10 minutes before serving. Beat heavy cream to soft peaks in the bowl of an electric mixer fitted with the whisk attachment. Add confectioner's sugar and vanilla, beat until well combined. Top trifle with whipped cream and garnish with chocolate shavings; serve immediately with hot fudge sauce.