The trick with lasagne is to make it in advance, and allow it to cool and 'set' - otherwise it will be runny and difficult to serve. You can reheat just before eating. I make our lasagne in advance and reheat.
Serves 6:
For the bolognaise sauce:
1 clove garlic crushed
1 onion chopped
2 carrots chopped
2 sticks celery chopped
150g pancetta or bacon
500g mince
1 glass red wine
400g chopped tinned tomatoes
up to 1 litre of stock (veg will do)
Fry garlic, veg, and pancetta for 10-15 mins until veg softened, but not browned; add mince and cook until brown, breaking up chunks; add wine and simmer until reduced; add toms and 250ml stock and seasoning. Simmer for 2 hours, adding stock and stirring as the sauce reduces; you want to end up with thick, but not solid ragu.
White sauce:
50g plain flour
50g butter
800 ml milk
cheddar cheese if desired
melt butter in pan, add flour and stir constantly for 2 mins - be careful not to burn the mixture; gradually add warmed milk until sauce is smooth; keep heating and stirring until white sauce is thick; add grated cheddar cheese for extra cheesiness if desired.
Grease a baking dish with tsp olive oil. Add one layer of lasagne pasta: scoop on 1/2 ragu; pour on 1/3 of white sauce. Add another layer of lasagne, Repeat with sauces. Finish with another layer of lasagne, cover with remaining 1/3 of white sauce; sprinkle over 50g grated parmesan.
Cook for 30-40 at 200 degrees C, or until parmesan is browned.
HTH!