Dry fry the lean minced beef until brown. Add the onion, garlic, celery, and fry until softened. Add the remaining ingredients, stir, and simmer for 20 minutes.
To make the cheese sauce, melt the butter in a pan, adding the flour and stirring well for about a minute. Slowly add the milk and bring to boil. Add the mustard and taking the pan off the heat, add 75g of the cheese.
In an ovenproof dish layer the mince mixture with lasagne sheets, creating 3-4 layers. Top with the cheese sauce, sprinkling the remaining cheese on top.
Place in the oven on the middle shelf for 45 minutes until the pasta is soft and the cheese is golden brown.