First bring a large pan of water to the boil and add the pasta. Cook according to the packet instructions. When the pasta is nearly cooked, add the broccoli to the pan and simmer for 2 minutes. Drain the water from the pan, retaining a little in a small jug.
Whilst the pasta is cooking, make the sauce. Heat a couple of tablespoons of water in the base of a large pan. Add the leeks with a pinch of salt and sauté for 5 minutes until soften. Add the, mushrooms and garlic and simmer for a couple of minutes until the mushrooms just start to release some fluid.
Make the sauce whilst the veggies are cooking. Pop the silken tofu, mustard, nutritional yeast, salt and pepper into a small blender or Nutribullet jug and blend to smooth.
Once the leeks and mushrooms are ready, pour in the sauce and simmer gently for a few minutes (probably just while the pasta finishes cooking).
Tip the cooked pasta and broccoli into the pan and stir well to combine. If the sauce is a little thick or dry, add a little of the retained pasta cooking water.
Serve in bowls with a little extra nutritional yeast and swirl of extra virgin olive oil or flaxseed oil if desired.