Lasagne for a family

This will feed up to 12 people (or else put it in the freezer!).
Ingredients:
700g mincemeat
3 carrots, 1 red pepper, 2 courgettes, 4 onions, 5 celery branches, 4 garlic cloves
40g tomato paste, 400g chopped tomatoes
1 glass red wine
butter, olive oil, salt, pepper, 1 bay leaf

For the Béchamel sauce:
50g butter
60g flour
1L milk