1. Chop and steam broccoli florets until bright green (about 3 to 4 minutes). Be careful not to overcook the broccoli; you want a little bite to it. Drain, rinse with cool water to stop the cooking, and set aside.
2. Boil peeled and chopped potatoes and carrots in a large pot of water for 15 minutes. Add cashews to the pot and continue boiling for another 3 to 4 minutes. Potatoes and carrots should be fork-tender. Strain potatoes, carrots, and cashews and retain the cooking water (set aside).
3. Add a half cup of the potato-carrot cooking water you set aside and all other ingredients to a high-speed blender with a vented lid. Blend and add more water until you reach the desired smooth and creamy consistency.
4. Bring a large pot of water to a boil. Cook pasta according to package instructions. You want your pasta al dente (or chewy and firm). Strain and return the pasta to the pot. Immediately stir cheese sauce into the pasta and carefully fold in the broccoli. If the cheese sauce has cooled, turn up the heat to medium-low to reheat for a few minutes, stir and serve.

Store leftovers in an airtight container in the refrigerator for up to 4 days.