Slice your onion into thin rings and sautée them in butter on a medium heat. Add cumin, nutmeg and smoked paprika, along with salt & freshly cracked black pepper to taste. When softened, add 2tbsp of water then cook on low heat with lid covered for another 20 mins
Sprinkle some olive oil on your buns and toast them in a dry pan until golden. Shape the mince into patties
Turn your pan up to a high heat, add some olive oil followed by your burger patty. Season with salt and pepper whilst in the pan and cook for 1-2 minutes per side
Slice the cheese, then move the burger onto an oven tray, cover with your cheese and place it under a pre-heated grill until melted
Assemble your burger with sauce of choice on each bun, followed by lettuce, then burger patty, then caramelised onions, covered with the top bun. Serve and enjoy!