Prep time: 15 minutes
Cooking time: About 12 minutes
1. Preheat grill to medium-high heat (if using oven, preheat to 375 degrees).
2. In a mixing bowl, combine ground meats, cheese, Worcestershire sauce, bread crumbs, salt, and egg, and mix well.
3. Coat an 8-inch square baking pan with cooking spray. Press the meat mixture firmly into the pan, loosen edges with a knife, then invert the pan onto a baking sheet. (The meat should slide out in the shape of a square.) Cut the large square of meat into 4 square burgers, and, with a spatula, place each square carefully onto the grill. Cook for 6 minutes per side, or until burger registers 165 degrees on a meat thermometer. Alternately, place the squares in a baking pan and bake at 375 degrees for about 30 minutes.
4. Cut focaccia into 4 equal squares, then slice each in half crosswise for the bun. Put burgers in buns and serve with desired toppings.
How kids can help: Measure and mix ingredients; garnish burgers.