Cheesy broccoli pasta bake

I had broccoli to use up, so this is what I made!

Half a head of broccoli
Handful of wholewheat pasta
Large knob of butter (about 1cm by 3cm by 4cm)
2 tablespoons of plain flour
1/2 teaspoon mustard powder
Milk
Parmesan and cheddar to taste
Parsley breadcrumbs (I froze what I had leftover from my herby crust salmon earlier in the month - just finely crumbed bread with salt, pepper and parsley)
Small onion, finely chopped
Salt and pepper to taste

1. I boiled the pasta in a large pan and and mid-way through cooking I added the broccoli, which I'd chopped into small florets
2. Make a cheese sauce by melting the butter, adding the flour and mustard powder to form a paste, slowly adding milk until it's the right consistency (thick and smooth) and then adding grated cheese in. At the end I added the onion - that's why it's important it's finely chopped, it doesn't get much heat exposure!
3. Then I added the sauce to the drained pasta and broccoli, gave it a good stir, popped the majority of it into a small pie dish (seriously, how cute?!) and ate the rest out of the pan like the greedy pig I am.
4. I sprinkled a layer of breadcrumbs on top and popped it in the oven at 180 degrees (fan) for 15 minutes

Serve it up with some clean and springy leaves. I was impressed how tasty this was given how few ingredients there were, and at least now there's broccoli in my tum and not going beige in the fridge! I don't know how but broccoli always tastes nicer when it's been baked a while!