Place ground beef, onion and garlic in a large pan and break meat into small pieces, until meat has browned, add a bit of salt. Then add ketchup, mustard, and mayo. Mix then add a bit more salt and pepper and ½ the bacon.
Pour beef mixture into the greased baking dish and spread evenly throughout. Pour cauliflower mixture on top and spread evenly throughout. Top with the rest of the bacon and a bit of black pepper.
Place in oven to bake for 20-25 minutes, until top has slightly browned.