Melt half the butter in a large pan over medium heat. Add the garlic and cook for about a minute until the garlic gets soft. Add artichokes and spinach, stir till combined and heated through. Add the sour cream and cream cheese. Heat until melted and smooth. Finally, add the Cheddar/Jack mix and stir until cheese is completely melted. Pour into a greased 8X8 dish. To make the topping: combine remaining butter, bread crumbs and parmesan cheese till crumbly. Cover the artichoke mixture with the cheese topping. Bake for 20 minutes. Let cool for about 10 minutes before serving