Place the heavy cream in a small pot, over low heat, to start warming up. You can't go too fast because the cream will boil up the sides of the pot and overflow and make a big mess of your kitchen. That’s never good.
While warming the cream, in a small bowl combine the powdered sweetener, xanthan gum and salt. Mix well, as this will help decrease the chances of the xanthan gum clumping. Set aside.
Place the egg yolks into a large mixing bowl. Once the cream is JUST beginning to simmer, slowly whisk it into the eggs. Then, put the hot egg mixture back into the pot. Stir quickly, so the eggs don't scramble.
Whisk in the dry ingredients, whisking while adding them. This should dissolve everything, further preventing scrambled eggs and eliminating xanthan clumps. Keep whisking, until the frothy bubbles stop forming on the surface, it thickens and coats a spoon.
Once the mixture coats the spoon and/or is about 165°F (74°C), add the peppermint syrup, almond milk, vegetable glycerin and vanilla extract. Taste the ice cream base. Add more sweetener or another dash of salt, if you’d like. When it cools and has air added by the churning, the flavors will calm. So, a little on the sweet side is ok.
Pour it into your ice cream machine, based on whatever method applies to your unit. Start it churning!
While the machine churns, make your ganache. Heat up your cream on the stove. Bring it to hot and is just about to simmer.
Place your chocolate chips and butter cubes into a small mixing bowl. Pour your hot cream mixture over the chocolate and whisk it in the bowl, until the chocolate is fully melted and incorporated. At this point, you can simply set the bowl aside (somewhere warm) and wait until the ice cream is soft, but ready. Different machines have different requirements. For mine, it’s best to turn the machine off, pour the fudgey concoction over the top of the ice cream and gently fold the chocolate into the ice cream base, then remove from the machine and freeze. Personally, I use an ice cream scoop to divide into individual portions, then freeze the cups. You can freeze in one big container, though.
Some machines can’t be turned off, while adding toppings, or folding is difficult. In this case, chill the bowl of ganache. Once cooled, you can use a tiny ice cream scooper, or a small spoon and make little balls/blops/noogins of chilled ganache and set them on a chilled plate/pan with parchment. This will make little fudge nuggets. Then, when moving the ice cream into their container(s), you can just drop a few nuggets into each container, as you adding the ice cream. This is another way to incorporate the fudge into nice big bites within the ice cream.
If you add the warm liquid fudge to a churning machine, you run the risk of the fudge being absorbed by the ice cream. This will still taste great, but you’ll have a mint-chocolate ice cream, rather than a nice peppermint ice cream punctuated with the occasional blast of fudgy goodness. It really all depends on your, your goals, your time, your machine, etc. All results will taste great!