Preheat oven to 375ºF. Grease a 9x9" pan and set aside.
Prepare frozen broccoli according to package directions. Once cooked, remove from the bag and chop broccoli pieces into small chunks.
Meanwhile, combine the cream cheese, half and half, mayonnaise, ¾ cup shredded cheddar, pepper, garlic salt, salt, and onion powder in a large bowl. Beat until fully combined. Add in reserved broccoli and gently stir to combine.
Pour dip into prepare baking dish. Top dish with remaining ½ cup shredded cheddar cheese and ½ cup mozzarella cheese.
Place in the oven and bake for 30-40 minutes or until the cheese has melted and browned slightly. Serve warm with bread or hearty crackers.
Recipe by SoFabFood at https://sofabfood.com/broccoli-cheddar-dip/