Add the milk, cream, and vanilla to a saucepan on medium heat. Whisk in the cardamom. Bring the liquid to a gentle simmer.

Vigorously whisk the yolks and sugar together in a bowl. When the cream is just starting to simmer (don't boil it), slowly pour some of the liquid into the yolks while whisking.

Pour the mixture back into the saucepan and turn the heat down to medium-low. Stir in a figure 8 motion with a wood spoon or rubber spatula for several minutes until slightly thickened. Remove from the heat. Allow to cool for several minutes, stirring periodically. Cover with plastic wrap that’s pressed directly against the liquid to prevent a skin from forming. Chill until very cold, preferably overnight.

Prepare ice cream according to the manufacturer's instructions.

Preheat the oven to 350 degrees F. Line a baking sheet with aluminum foil and spray lightly with baking spray.

In a medium bowl, combine the melted butter, brown sugar, maple syrup, cinnamon and cayenne. Stir in the pistachios, coating to evenly combine, and then pour them onto the foil-lined baking sheet and spread them in an even layer.

Bake for 10 minutes, stirring halfway through. Remove the nuts from the oven and allow them to cool and crisp up on the baking sheet.

Once cool, break the nuts apart or chop them coarsely.