Finely chop the onion and garlic. Slice the celery, mushrooms, sun-dried tomatoes and bacon.

In a large pan, add bacon pieces and gently fry in olive oil until golden and crisp. Add the mushrooms and briefly cook until browned. Transfer mushrooms and bacon to a small dish and put aside.

Wipe out the pan, add a little more oil and put on a medium low heat. Add the onion, celery and garlic and cook gently until the vegetables are soft.

Increase the heat to medium and add the minced beef. Cook until the meat is no longer pink. Season with salt and pepper. Add thyme and oregano.

Add the wine and stir the mixture until the alcohol evaporates.

Reduce the heat back to medium low. Add the cooked mushrooms and bacon, as well as the tinned tomatoes, tomato puree, and sun-dried tomatoes. Stir well and cover. Turn the heat to low and simmer (stirring occasionally) until the liquid has reduced down and the mixture is no longer wet (or, conversely, if the mixture is too dry, add water). This should take at least one hour. When almost cooked, add the peas.

Remove the meat sauce from the heat and let cool. If not using straight away, it can be stored in the fridge for several hours, or frozen until needed at a later date.

Heat the butter in a large pot over a medium/high heat. Once the butter has melted, add the flour and stir quickly to absorb the butter. As soon as it has combined, add about a quarter of the milk and stir quickly to combine. As soon as it has combined, add another quarter of the milk. Repeat until the milk is used up (you may need more or less milk depending on how thick you like the sauce). Turn the heat down to low and add the grated cheese and mustard, stirring to combine. Add salt and pepper to taste. Put aside (once cool, can be refrigerated until needed).

Preheat oven to 180˚C. Spread half of the meat sauce onto the base of a large baking dish. Layer with half of the lasagne sheets, then half of the white sauce. Repeat – half meat sauce, half lasagne and finishing with the rest of the white sauce. Sprinkle with a bit of extra grated cheese and cover with tinfoil. Bake for 40 minutes then uncover, turn the heat to grill (broil) and bake a further 10-15 minutes until the topping is golden brown.