Pumpkin & Broccoli Pasta Bake

I made this casserole when I was in a baked macaroni and cheese sort of mood, but lacked a few ingredients and the inclination to go grocery shopping. Using the awesome power of my imagination, it occurred to me that a pumpkin-based sauce with the same seasoning profile might get us to a similar place, and the end result was more than good enough to merit a blog post of its very own.

Pumpkin & Broccoli Pasta Bake
Ingredients
~ 1 lb. pasta (I used fusilli)
~ 1 pound fresh or frozen broccoli, cut into bite-size pieces
~ 6 cups plain, unsweetened soy milk
~ 2 tbsp. "no chicken" bouillon
~ 2 bay leaves
~ 1 tbsp. each: prepared mustard, vegan Worcestershire sauce, hot sauce (I like Frank's)
~ 1 generous tsp. Marmite
~ 2 tbsp. olive oil
~ 1 ginormous yellow onion, diced
~ 4 cloves garlic, minced
~ 1 tsp. each: sage, thyme
~ 1/2 tsp. each: smoked paprika, white pepper
~ Dash nutmeg
~ 1/2 cup nutritional yeast
~ 2 cups grated vegan mozzarella (I used TJ's)
~ 1 15 oz. can pureed pumpkin (about 2 cups)
~ 1 cup breadcrumbs, store bought or homemade
~ Dash each: salt, black pepper, paprika

Directions
~ Preheat the oven to 400 degrees fahrenheit and coat a casserole with cooking spray.
~ In a large beaker, whisk together the soy milk, bouillon, mustard, Worcestershire sauce, hot sauce, and Marmite. Add the bay leaves, cover, microwave until hot (you can also do this in a large saucepan, obviously), and set aside.
~ Heat the olive oil in a large saucepan and sauté the onion over medium heat for about 10 minutes, until quite soft but not browned.
~ Add the garlic and dry seasonings and cook about 5 minutes more, until fragrant.
~ Stir in the nutritional yeast and then gradually add the soy milk mixture, stirring continuously.
~ Gradually add the mozzarella and the pumpkin puree and keep stirring, until the cheese melts and you have a smooth, pumpkin sauce. Taste for seasoning, remove the bay leaves, and set aside.
~ Boil the pasta according to package directions; add the broccoli in the last two minutes of the cooking time and then transfer the whole business to a colander to drain.
~ Combine the cooked pasta and broccoli with the pumpkin sauce.
~ Transfer the mixture to your greased casserole and top with the breadcrumbs, a sprinkle of salt, pepper, paprika, and a good shot of cooking spray.
~ Cover with foil and bake at 400 degrees for 20 minutes, then remove the foil and return to the oven for another 15-20 minutes, until browned and bubbling.
~ Remove from the oven and allow the casserole to rest a few minutes before serving.