Gorgeous Greek pasta meal -- 4 Cheese lamb Pastitsio

Here's where we re-used the braising liquid from our neck of lamb after removing the fat. What results is a low-cost, very rich, high lamb flavor dish. Gorgeous.
To recap the bechamel sauce: Melt 80 grams of butter, add 3 tablespoons of flour and cook a little bit. Don't over-brown the roux. Add 3/4 cup milk and cook gently for 2-3 minutes. Add your cheeses -- what have you? -- and then one beaten egg. Adding the cheeses will cool the sauce so the egg shouldn't separate, but whisk vigorously to make sure. Then just spread over the Pastitsio and top with more cheese if you have it.
35-45 minutes at 350F. If you're using a fan oven 35 mins will probably do it.
This yielded 8 generous portions, which are great for frozen meal prep, BTW.