In a medium saucepan, combine heavy whipping cream, whole milk, granulated sugar, and Dutch process cocoa powder. Heat over medium heat until it reaches a gentle simmer.

Whisk together the large egg yolks and remaining sugar in a heat-proof bowl until pale and fluffy.

Gradually pour a small amount of the warm dairy mixture into the egg yolk mixture while whisking continuously.

Pour the tempered yolk mixture back into the saucepan, stirring over medium-low heat until thickened.

Remove from heat, add chopped dark chocolate and vanilla extract, stirring until melted and smooth.

Transfer the custard to a bowl, cover with plastic wrap, and refrigerate for at least 8 hours.

Pour the chilled custard into your ice cream maker and churn until soft-serve consistency.

Gently fold in mini marshmallows, roasted almonds, and finely chopped chocolate.

Transfer to an airtight container, smooth the top, and freeze for at least 4 hours before serving.