I recommend making the sweetened condensed milk as part of the recipe vs. before hand since it needs to be measured when liquid.
Fill mini molds half way with liquid keto condensed milk. Set aside. This allows it to start to thicken.
In a medium bowl, melt chocolate in microwave for 90-120 seconds. You can also melt it on the stove. Stir often.
Add butter and heat for 20 (ish) seconds longer.
Stir and allow remaining chunks to melt.
Add remaining ingredients and combine well.
Add a dollup of chocolate to each mold.
Using a toothpick, stir it around a bit.
Freeze for at least 6 hours (I recommend over night).
Note
The sweetened condensed milk portion will thaw quickly, so keep them frozen until you want to eat them. I keep them in a bowl in my freezer and just pop 1 or 2 on occasion!