Pepper cheese burger

Ingredients

Persons-+
• 44 slices of pepper Gouda
• 25 25 grams butter
• 4 4 hamburgers
• 2 2 onions, cut into thin rings
• 4 4 rolls
• 2 2 tablespoons tomato ketchup or red pesto
• 1 1 tablespoon freshly chopped parsley, chives or thyme