Step 1Preheat oven to 180°C. Place sweet potatoes in a microwave-proof dish with 2 tablespoons of water. Cover and microwave on high for 8–10 minutes, or until tender. Drain and set aside.
Step 2Meanwhile, heat the olive oil in a large non-stick frying pan over high heat. Add the garlic, oregano, chilli flakes and mince, then fry mixture for 6–8 minutes, or until browned. Add tomatoes and Worcestershire sauce, then boil for a further 10 minutes, or until the sauce has thickened.
Step 3Spoon half of the mince mixture into a medium, deep ovenproof dish. Completely cover mince with half of the sweet potatoes. Spread with half of the cottage cheese, followed by half of the spinach. Repeat the layers in the same order. Scatter with grated cheese and season with cracked black pepper, then press lasagne down lightly to compact the layers a little.
Step 4Bake lasagne for 15 minutes, or until cheese is melted and golden. Serve with steamed broccoli.