Broccoli and White Bean Gratin

I know I said I was all about lighter Spring food, but this isn't it. This is actually not all that unhealthy, the base is broccoli and white beans, and the sauce is mostly lowfat milk.
Also, I blasted music and danced around the kitchen while I was making it.  That doesn't have anything to do with the recipe.  It does make cooking extra fun, though.  You might want to try it when no one is home.

Broccoli and White Bean Gratin
pieced together from a bunch of recipes online

1-2 pounds broccoli florets (I used fresh, but frozen and thawed would work as well)
2 Tablespoons olive oil
1/2 cup chopped onion (1 small)
3 cups milk (I used 1%)
1 teaspoon dried thyme
1 clove garlic, minced
1/8 teaspoon nutmeg
salt and pepper
1/4 cup flour
2/3 cup grated parmesan cheese (I used half parm and half asiago)
2 15 oz. can cannellini beans
1 slice whole wheat bread, or 1/2 cup bread crumbs

Preheat oven to 400 degrees.
In a large pot, steam the broccoli florets for 2-3 minutes.  Drain and set aside.

Drain and rinse cannellini.  Make note to get a contrasting color for the next colander so everything doesn't look so...yellow.

Heat 1/2 Tablespoon olive oil in the same pot, and add chopped onions.  Saute for 2-3 minutes.

Add the garlic, thyme, nutmeg, and cook for 1 minute more.

Pour in 2 1/2 cups milk and heat on low for 10 minutes.

Mix flour into the remaining 1/2 cup milk.  

Whisk the flour mixture into the pan and cook over medium heat until thick, stirring frequently.  I consider it thick enough when I can see the bottom of the pan for a second when stirring.

Remove from the heat and stir in half the cheese, salt and pepper.

Mix the beans and broccoli into the milk and cheese mixture.

Transfer mixture to a shallow baking dish.  Mine is 2 quarts, I think.  Emile Henry dishes aren't very clear about measurements.  You could go a little bigger, but I wouldn't recommend going smaller, because it was pretty full.

If you are making your own breadcrumbs, toast a slice of bread and put into a food processor.  This is a perfect job for the mini food processor.  A few seconds turns this:

Into this:

Mix remaining cheese in with breadcrumbs.  I just added it to the food processor and ran it for a few pulses.  Sprinkle breadcrumb mixture over vegetable mixture.

Bake at 400 degrees for 20 minutes, or until bubbly and golden brown.

When you are wrapping up the leftovers, don't drop the foil roll onto the floor, because it doesn't roll back up nicely, and you will have a big mess.