Preheat oven to 325°F (160°C). Place six 6-ounce ramekins in a deep roasting pan and set aside.

In a medium saucepan, combine heavy cream and ground pistachios. Heat over medium heat until small bubbles form around the edges, about 5 minutes. Remove from heat, cover, and let steep for 15 minutes to infuse the pistachio flavor.

Strain the cream through a fine-mesh sieve into a clean bowl, pressing on the solids to extract all liquid. Discard the pistachio solids and stir in the milk.

In a large mixing bowl, whisk together egg yolks, 1/3 cup sugar, vanilla extract, and salt until smooth and pale, about 1 minute. Slowly pour the warm pistachio cream into the yolk mixture while whisking constantly to prevent curdling.

Divide the custard evenly among the ramekins. Pour enough hot water into the roasting pan to come halfway up the sides of the ramekins, creating a water bath.

Carefully transfer the pan to the oven and bake for 35-40 minutes, until the edges are set but the centers still jiggle slightly when gently shaken.

Remove ramekins from the water bath and let cool to room temperature, about 1 hour. Cover each with plastic wrap and refrigerate for at least 4 hours or up to 3 days.

Just before serving, remove custards from the refrigerator and blot any condensation from the tops with a paper towel. Sprinkle 1 tablespoon of sugar evenly over each custard.

Using a kitchen torch, hold the flame 2-3 inches from the surface and move in circular motions until the sugar melts and caramelizes to a deep amber color, about 1-2 minutes per ramekin.

Let the sugar harden for 2-3 minutes before serving for the signature crispy top.