Instructions:
- Thaw the spinach completely. Wrap it tightly in a clean tea towel or paper towels and squeeze out as much liquid as humanly possible. Chop the drained artichoke hearts into bite-sized pieces. Mince the garlic.
- In a large mixing bowl, combine the softened cream cheese, mayonnaise, and sour cream/yogurt. Beat until smooth and lump-free.
- Mix in the minced garlic, Worcestershire sauce, onion powder, salt, and pepper into the cream cheese mixture until evenly incorporated.
- Gently fold in the dried spinach, chopped artichokes, Parmesan cheese, and half of the shredded mozzarella and Jack cheeses. Mix until everything is just combined.
- Scrape the entire mixture into the bottom of the lightly greased slow cooker insert. Smooth the top evenly with a spatula.
- Sprinkle the remaining half of the mozzarella and Jack cheeses evenly over the surface. Place the lid on and cook on LOW for 3–4 hours or HIGH for 1.5–2 hours, until the dip is heated through and the edges are bubbling gently.
- About 15 minutes before serving, remove the lid. If the top isn't brown, switch to HIGH or briefly transfer to an oven-safe dish and broil for 2–3 minutes until golden brown. Watch carefully to prevent burning.
- Stir lightly before serving warm directly from the Crockpot, keeping it on the WARM setting.