Prep the ingredients. Roughly chop the spinach and artichoke hearts. Cube the vegan cream cheese so it melts faster. Mince the garlic and chop the onion.
Combine everything in the slow cooker. Add the spinach, artichokes, cubed vegan cream cheese, vegan sour cream, shredded vegan mozzarella, grated vegan Parmesan (or nutritional yeast), chopped onion, minced garlic, black pepper, and salt to the crockpot bowl. Toss briefly with a silicone spatula so the ingredients mingle.
Slow cook. Cover and cook on low for 2–3 hours or on high for 1 hour, checking every 30 minutes to prevent overheating. Once the cheeses melt and the dip looks silky and slightly bubbly, it’s ready. Slow cookers vary, so keep an eye on it.
Stir and finish. Stir the dip until you get a smooth, even texture. Taste and adjust salt and pepper. If you like, add a pinch of smoked paprika or a squeeze of lemon for brightness.
Serve warm. Transfer to a serving dish or keep it in the Crock-Pot on the “warm” setting while guests graze. Serve with tortilla chips, toasted baguette slices, pita, or crudités.
Reminder: Check early and often — slow cookers differ, and soft vegan cheeses can go from perfect to overly oozy if left unchecked.