a "healthy" take on a classic

For dinner tonight, I wanted something comforting.  But post-baby food and comfort food don't work so well together, so I had to come up with a compromise, and I think I did a great job.  I've made a healthier mac & cheese on here before, I think, but this time I used whole wheat macaroni (that you can get at Walmart for $1!!), and lots of broccoli.  I actually don't really like mac & cheese too much as a whole meal because I really like vegetables and variety in my food.  So if you're not a fan of messing with a classic like smooth & creamy mac & cheese, this isn't the recipe for you.  But I'm a fan, and my little girl sure loved it!  And she never eats normal mac & cheese.  And my picky-eater husband really liked it, so I think it was a success.

1 box whole wheat macaroni
1 large head of broccoli, chopped (or an equivalent of your favorite green vegetable)
1/2 onion, chopped fine
2 T olive oil
1 T butter
1/2 T dijon mustard (I used the grainy mustard)
3 C milk (I used 1.5 C of 1% and 1.5 C whole.  I don't recommend using any less fat or the sauce will turn out a little gluey)
3 T flour
4 oz extra sharp cheddar cheese, grated or cut into small cubes
4 oz Pecorino Romano cheese, grated fine
salt and pepper to taste

1. In a large pot, bring water to a boil, and cook pasta to just under al dente.  Add the broccoli for the last 30 seconds or so and drain.  Set aside.
2. Meanwhile, in a medium sauce pan, heat the olive oil and butter until butter is melted.  Add onions and cook,stirring often, until softened.
3. Once the onions are cooked, sprinkle the flour and stir quickly (you can switch to a whisk at this point if you want) until flour takes on a slight golden color and no longer smells raw.  Slowly pour in the milk, about 1 C at a time, stirring constantly.  Once the sauce is thickened, add the mustard and cheese, and cook until the cheese is completely melted and well encorporated.
4. Add the pasta and broccoli into the sauce and stir until the pasta is thoroughly coated.  Pour into an oven safe dish, sprinkle extra cheese on top (or toss some finely grated cheese with some panko breadcrumbs and sprinkle that on top for a nice crispy topping) and place in a 450°~500° oven for 5~10 minutes, until cheese is bubbling and top is golden brown.  Serve hot.