This tasty veggie bake is easy to prepare and light on the milk fat. If that's not a concern, you can make it more traditional - and richer - by using full cream milk and doubling the sauce ingredients. If you want to use fresh spinach, wilt a little beforehand and drain well before baking.
If you are in a hurry, use a microwave safe casserole dish, cover with plastic wrap, and cook on high for 3 minutes. Release the steam, recover, and cook on high for another 3 minutes.