Remove long, obvious stems from the fresh spinach and roughly chop the leaves. Drain the jarred artichoke hearts and roughly chop them; if using frozen artichoke hearts, thaw, drain, and roughly chop. Finely mince the garlic and cube the cream cheese.

Place a 6- to 7-quart slow cooker on the counter. If you wish, line it with a slow cooker liner for easier cleanup.

Add the chopped spinach, chopped artichoke hearts, cubed cream cheese, sour cream (or Greek yogurt substitution), mayonnaise, shredded mozzarella, shredded parmesan, minced garlic, salt, and pepper to the slow cooker.

Stir the ingredients together as best you can so the cream cheese begins to break up and the ingredients are distributed. Use a spoon or spatula to press and break up cream cheese cubes if needed.

Place the lid on the slow cooker and cook on LOW for 1 hour.

Remove the lid and stir thoroughly, scraping the sides and bottom so any remaining cream cheese is incorporated and the mixture is even.

Replace the lid and continue to cook on LOW for 1 additional hour, or until the dip is hot, the cheeses are melted, and the mixture is bubbly.

Turn off the slow cooker and serve the dip hot with bread, crackers, tortilla chips, or veggie sticks as desired.

Make-ahead: the dip can be made a few hours before serving; keep it on the LOW setting (or the WARM setting if your slow cooker has one). Note the dip will thicken the longer it cooks/holds on LOW or WARM.

Storage: cool any leftovers, store airtight in the refrigerator for up to 5 days, and reheat gently in the microwave or by other preferred methods. Freezing leftover dip is not recommended.