Preheat oven to 325˚. In a heavy-bottomed saucepan, combine cream, milk, sugar, vanilla extract, and espresso powder. Cook over medium-high heat, stirring constantly, until mixture just begins to boil.
In a medium bowl, whisk egg yolks until smooth. Ladle 1 cup hot cream mixture into eggs, whisking constantly. Repeat with remaining cream mixture. Pour egg mixture into saucepan; whisk to combine.
Divide mixture among pot de crème cups. Place cups in a roasting pan. Fill pan with enough water to come halfway up sides of cups. Cover pan with foil; bake for about 1 hour and 20 minutes. Remove from oven; remove foil. Let pots de crème cool in pan for 30 minutes. Remove from pan and refrigerate for at least 4 hours. Serve immediately, or refrigerate, covered tightly with plastic wrap, for up to 1 week.
Recipe by Victoria at https://victoriamag.com/coffee-pots-de-creme-recipe/