Get a large pot (we're going to be using it as a mixing bowl eventually to save dishes; Dutch oven size is ideal), and put in it enough water to cover the broccoli that you are going to be cooking. No need to salt the water; the salt won't penetrate the broccoli anyway or help the cooking temperature, so you're just wasting salt at this point in the cause of myths. Cover the pot and put the pot on to boil.

Crush the garlic and set aside.

Mix the breadcrumbs, ground walnuts (not the whole ones), sage, and the two tablespoon butter zapped to melt in microwave, and set aside.

Crumble the cheese, set aside.

Cut the broccoli into bite-size pieces (if you're using frozen, no need). Don't forget to peel the stalks and chop them up, too.

When the pan of water has boiled, cook the broccoli in it for 4 minutes, then drain it, and set aside. Refill the pot with water with a tidge of salt in it (to help flavour the pasta), and set it back on to boil water for the pasta.

Melt the 6 tablespoons of butter in a saucepan with the nutmeg, and some pepper to taste. (Heating the nutmeg and pepper at this point helps fully develop their range of flavours.) Add the flour and the garlic, and cook a bit while whisking it until white froth appears. The white froth indicates that the flour is cooked. Then whisk in the milk, and cook at a low heat whisking a few times until the thickening has kicked in (about 4 to 5 minutes.) Whisk in the mustard and two-thirds of the cheese.

Cook the pasta. Drain. Put back in the pot. Add the sauce, stir to cover, then fold in the walnut pieces and broccoli.

Pour pasta mixture into a dish that can go into the oven. Sprinkle with the breadcrumb mixture. Place in the oven and cook uncovered until the breadcrumbs are golden and the sauce is bubbling.