To make 1 pint you need to double the recipe shown here. So that will be:
4 tablespoons flour
4 tablespoons butter
2 cups milk
½ tsp salt.

You make it extra thick, add an additional tablespoon of flour.

If necessary, you can add more flour after you’ve made the sauce (before you’ve added the cheese) by mixing the flour and a little milk in a cup until the mixture is smooth.

Then add it to the saucepan and stir well till the sauce is bubbling again.

We’ve done some thinking about your query about how to make lasagne for two, when one does not like garlic and onion.

Our thoughts are:
1 Cook the meat mixture without garlic or onion. While the meat is cooking, cook the onion and garlic separately. When the meat mixture is cooked, divide it into two portions and add the onion and garlic to one portion.
2 Either make the lasagne in two separate dishes, or use one dish and carefully put the onion and garlic meat mixture into one part of the dish. You could keep it separate with a piece of aluminium foil.

Hope this helps. Let us know how you get on.
Judy

Awsome