Set a medium bowl in a large container of ice water.
Whisk cream, almond milk, sweeteners and cocoa powder in a medium saucepan until cocoa powder is mostly dissolved. Over medium heat, stir occasionally and heat until mixture is steaming but not simmering, or 170F on a candy thermometer.
Whisk egg yolks in a small bowl until smooth. Very slowly whisk in 1 cup of the hot cream mixture to temper the yolks. Then slowly whisk tempered yolks back into cream mixture, stirring constantly. Continue to cook until very hot, 175 – 180F.
Add chopped chocolate and let sit 1 minute to melt, then whisk to combine.
Pour mixture into bowl in ice bath and let cool 10 minutes then wrap tightly with plastic wrap and refrigerate at least 3 hours.
When ready to churn, remove custard from fridge and add vodka, stirring to combine. Sprinkle with xanthan gum and whisk vigorously to combine.
Pour mixture into canister of an ice cream maker and churn according to manufacturer's directions. When ice cream is about the consistency of soft serve, transfer half to an airtight container.
Working quickly, add about half the peanut butter by spoonfuls. Add the remaining ice cream and the remaining peanut butter and swirl with a knife to spread evenly.
Press plastic wrap flush to the surface and freeze until firm, 1 to 2 hours.