Cook the mince and onion, stirring until the mince browns. Add the garlic, stir in and cook for 1 minute.
Add the carrots, mushrooms, oregano, tomatoes and puree. Dissolve the stock cube in 150ml hot water and add to the pan.
Meanwhile, preheat oven to 190C/Gas Mark 5. Melt the butter in a small pan then stir in the flour. Cook over a low heat for 1 minute, stirring all the time. Remove from heat and stir in milk. Heat until boiling, whisking all the time, then simmer for 1 to 2 minutes. Add most of the Scottish Pride Cheddar and season.
Pour meat sauce in a deep ovenproof dish, about 18cm x 23cm. Cover with half the lasagne sheets and pour over half the cheese sauce. Repeat the layers, finishing with cheese sauce, and sprinkle with the rest of the Scottish Pride Cheddar. Bake for 45 minutes.