Chocolate Pots de Crème

Setup - Set a rack in the middle of the oven. Preheat the oven to 300°F.

Heat the cream and milk - In a large saucepan, heat cream and milk to a simmer over medium heat, about 3 to 4 minutes. Whisk occasionally to prevent any milk at the bottom of the pan from burning.

Melt the chocolate - Remove the saucepan from the heat. Place the chocolate pieces into a small bowl. Using a ladle, spoon 1/2 cup of the liquid into the bowl and stir in chocolate, constantly whisking until the chocolate fully melts. Pour the chocolate liquid back into the saucepan, whisking frequently until the mixture is completely homogeneous. You don't want to see any small bits of chocolate here (otherwise, the custard may not set properly). If you do see small bits floating in the liquid, set the pan back on low heat, whisking constantly to melt any remaining chocolate. Then, remove the saucepan from the heat.

Whisk the eggs - In a small bowl, whisk the egg yolks and sugar for about 1 minute until the mixture lightens in color from bright yellow to medium yellow and thickens slightly. You're not looking for the ribbon stage, where the yolks lighten to a pale yellow; we're simply incorporating a little air into the yolks for a lighter custard.

Temper the eggs - Using a ladle, spoon 1/2 cup of the hot chocolate milk into the yolk mixture. Whisk constantly, to prevent curdling, until the liquid is homogeneous. Spoon another 1/2 cup of the milk and whisk again until fully combined. Pour the milk-yolk mixture back into the saucepan, whisking to combine.

Stir in remaining ingredients - Stir in the espresso powder (if using), kosher salt, and vanilla extract.

Strain the chocolate base - Then, strain the chocolate base by pouring it through a fine-mesh sieve into a large bowl. This step helps get out any curdled egg yolk that will affect the texture of the custard.

Fill ramekins - Place 6 (4-ounce) ramekins in a 9 x 13-inch baking pan. Fill each ramekin about three-quarters of the way full (or up until the inner rim).

Prepare the water bath and cover with foil - To prepare the hot water bath, use a hot water kettle or spouted measuring cup to fill the pan with hot tap water until it reaches two-thirds of the way up the sides. Next, lay a sheet of aluminum foil on top of the pan, covering loosely on all sides. Use a fork to prick the foil in several places to help steam escape (avoid pricking holes directly on top of the ramekins).

Bake the pots de crème - Open the oven and pull out the middle rack. Carefully transfer the pan to the oven, then slide it onto the rack. If you're worried about spilling, you can also place the pan on the rack before adding water and covering with foil. Once on the rack, carefully pour in the water and loosely cover with aluminum foil, pricking a few holes. Bake for 40 to 50 minutes, or until the outsides of the custards are set and form a dark ring, but the middle is still a little jiggly.

Cool - Gently remove the pan from the oven. Using oven mitts, carefully remove each ramekin from the pan and place onto a wire cooling rack (if you need to, feel free to let the ramekins cool for about 10 minutes before taking them out of the pan). Let cool at room temperature for about 1 hour, or until the ramekins are no longer warm to the touch. Then, wrap each custard in plastic wrap and chill in the fridge for at least 4 hours (but preferably overnight) before serving.

Serve and storage - Just before serving, remove ramekins from the fridge. Dollop a spoonful of whipped cream onto each custard. Top with chocolate shavings and a sprinkle of flaky salt. Cooked chocolate pots de crème keep in the refrigerator, covered, for 2 to 3 days.