In a small saucepan over medium heat, melt butter. Add garlic; cook and stir for 1 minute. Add cream; cook until liquid is reduced by half, 15-20 minutes. Add the Parmesan cheese, salt and pepper; cook and stir until thickened. Remove from the heat; stir in parsley. Cool slightly., Place crust on an ungreased baking sheet; spread with cream mixture. Top with chicken, mushrooms, spinach and mozzarella cheese. Bake at 450° for 15-20 minutes or until cheese is melted and crust is golden brown.