Add all the cheese ingredients to a high speed blender and process until smooth. It will be very runny.
Place the cooked rice and broccoli florets in an oven safe dish, measuring 8x12, or similar. Then pour the cheese sauce over the rice and broccoli, and mix well to evenly coat and distribute.
Bake for 20 minutes, mixing at the halfway point. Add a touch more milk if your cheese sauce gets too thick.
Optional but recommended: Broil your casserole for 2-3 minutes to brown the top.
If you don't have fresh broccoli, you may sub for frozen.For nut free, you may sub the cashews with sunflower seeds, with similar results. I find cashews a little richer here, so unless you cannot eat cashews, I don't recommend making the switch.If you do not have a high speed blender, soak your cashews in boiling hot water and then drain, before adding to your blender. This will help them break down into a smoother consistency. Alternatively, you may strain your cheese sauce once blended, using a nut milk bag.Once blended, your cheese sauce will be very runny but it will thicken in the oven as it cooks.If your cheese is getting too thick in the oven, add a splash or two more of milk and mix well to get it creamy again.This dish is best enjoyed hot from the oven, as the cheese sauce will thicken as it starts to get cold.Leftovers keep refrigerated for 2-3 days. Reheat leftovers to return the cheese sauce to a creamier state.