Slow Cooker Witch's Brew Recipe

Happy almost-Halloween! We had a play date today, and my 5-year-old taste-testers couldn't get enough of this stuff. The comments I overheard were priceless: "it doesn't taste like there are spiders or lizards or bugs in it" "how did your mom even know how to make this?" "is my tongue green yet?" "I've never had ice cream in a drink before" "I guess this is why witches have green