Mix together the ingredients in a the base of a slow cooker with a spoon.
1 cup sour cream, 1/4 cup mayonnaise, 8 ounces cream cheese, 14 ounces artichoke hearts, 5 ounces frozen chopped spinach, 1/2 cup mozzarella cheese, 1/4 cup Parmesan cheese, 1/2 tablespoon Worcestershire sauce, 2 garlic cloves, 1 teaspoon kosher salt, 1/4 teaspoon black pepper, 1/8 teaspoon cayenne pepper