1. Stir the ground meat with salt and freshly ground black pepper. Form the meat into 4 burgers.
2. Melt the butter in a saute pan until golden. Fry the burger about 1½ min. on each side over medium heat for about 2 min. Cover the pan with a lid, remove it from the heat and let the burgers rest.
3. Warm up the buns in the oven and cut them in half. Spread them with mayonnaise and top the bottom bun with lettuce.
4. Add the burgers and top with a slice of Castello® Burger Blue and sliced radicchio. Finish with the top bun and serve with chips.