Instructions

• Make the custard base: Combine the heavy cream and mint in a 3-quart saucepan. Heat over medium heat until small bubbles form and it starts to steam, about 6 to 7 minutes. Remove from heat and let the mixture steep for 20 minutes.
• Strain out the mint leaves using a fine mesh strainer, pressing the liquid through the leaves to extract all the mint flavor. Return the mint-flavored heavy cream to the saucepan and heat until it's steaming again, but not boiling.
• Add the milk, sugar, cocoa powder, and salt. Cook over medium heat until the sugar dissolves and the mixture is steaming with small bubbles forming, about 6 to 8 minutes.
• Whisk the egg yolks in a medium bowl. Gently heat the egg yolks by slowly adding ½ cup of the warmed chocolate cream to the egg yolks while continuously whisking. Add another ½ cup of the chocolate cream and temper the egg yolks again. This process is called tempering the eggs, and its purpose is to prevent the eggs from curdling while the custard cooks.
• Pour the warmed egg mixture back into the saucepan with the remaining chocolate cream. Bring the mixture to a simmer over medium heat (don't let it boil). Cook until the custard has thickened, stirring constantly, about 4 to 6 minutes. It should coat the back of the spoon and leave a trail when you draw your finger through it.
• Strain the custard through a fine mesh strainer into a clean bowl. If the custard boiled during thickening, straining it out will help remove any curdled bits of egg. Add the chocolate wafers (or chopped chocolate) and stir until melted, although the custard doesn't have to be completely smooth. Stir in the vanilla extract.
• Cool the base using an ice bath (equal parts ice cubes and water, reaching halfway up the sides of the bowl). Stir the custard occasionally until it's cooled to room temperature (a digital thermometer should read about 80 °F).
• Place a piece of plastic wrap on the surface of the custard and refrigerate until chilled, at least 4 hours or overnight. Chilled custard can be kept in the refrigerator for several days. For the best results, make sure the base is about 40 °F prior to churning.
• Churn the ice cream: Stir the chilled custard well. Pour it into an ice cream bowl and select the ice cream mode. As the mixing and freezing proceed, the volume of the base will increase.
• Add the mix-ins: Once the ice cream begins to thicken but is still soft, add the chocolate cookie crumbs into the ice cream. Once that has mixed in, spoon in 1½ cups of the marshmallow creme, leaving discernible streaks throughout.
• Continue churning until the ice cream has thickened more.
• Ripen the ice cream: Transfer the ice cream to a freezer-safe container. If you want, you can add in more of the marshmallow creme, streaking it through with a small offset spatula. When you're satisfied with the amount and distribution of the creme, smooth the top. Freeze the ice cream for 2 to 4 hours to allow it to firm up, a process called ripening.
• Serve with extra sprinkles of the chocolate cookie crumbs and enjoy!
• Storage instructions: Homemade ice cream will last for up to a month in a plastic freezer container placed in the rear of the freezer. After that, the ice cream may develop ice crystals and lose its creamy texture.