Melt butter in a large nonstick skillet over medium heat. Add green onions and garlic; sauté 4 minutes or until tender. Add cream and artichokes. Bring to a boil; reduce heat, and simmer 4 to 5 minutes or until reduced to 2 cups.
Beat cream cheese in a large bowl until smooth and creamy. Stir in water chestnuts and next 5 ingredients. Add artichoke cream sauce; stir until well combined. Gently fold in crabmeat.
Spoon dip into a lightly greased 3- or 4-quart slow cooker. Sprinkle with Cheddar cheese. Cook, covered, on LOW 2 1/2 hours or until thoroughly heated and cheese melts. Serve with toasted baguette slices or crackers.