Place the espresso and heavy cream and vanilla paste in a medium sized saucepan and bring to a boil.

Mix together the sugar, cornstarch and egg yolks in a bowl. Slowly add the hot coffee to the egg mixture a small amount at a time so as not to curdle the eggs.

Pour the mixture back into the saucepan and return to the stove and cook until it begins to thicken, stirring constantly. Once it’s thickened, remove from heat and transfer to a bowl and cover it with plastic wrap. Press the wrap down directly on the surface of the custard to avoid it creating a crust on top. Place it in the refrigerator to thoroughly chill–about 2-3 hours.

Preheat the oven to 400 degrees.

Place water, butter and salt into a medium sized pan and bring to a boil on the stove. Once it’s boiling and butter has melted, add in the flour. Using a wooden spoon, or danish dough whisk (https://a.co/d/d20uMkN) until the flour is fully mixed, cook over low heat for about 1-2 minutes to lose the flour taste. Remove from heat and add in the eggs, one at a time, beating vigorously until incorporated. Repeat until all the eggs have been added.

Scoop dough into a large piping bag and cut the tip off to create about a ½” opening. Pipe 4” long lines of dough onto a baking sheet, leaving about 2” space between. Place in the oven at 400 degrees for the first 15 minutes, then drop the temperature to 350 for an additional 5-10 minutes until they are golden brown. Do not open the oven when switching temperatures.

Cool the shells on the baking pan and once completely cool, slice lengthwise down the entire shell. Spoon the filling into the boat created and replace the top of the shell.

Heat the heavy cream to not quite boiling. Pour over the chocolate chips and allow them to melt. If they haven’t completely melted, place in the microwave for 10 second bursts, stirring each time you stop it. Stir until the chocolate is silky smooth. Pour into a piping bag and cut a small hole at the tip and drizzle chocolate over the top of the shells.