Bring a large pot of water to a boil. Add the cauliflower and cook for about 6 minutes or until soft when poked with a fork.
Use a fine-mesh strainer or slotted spoon to remove the cauliflower and add to a blender. Add the spinach milk, cheese, butter, salt, and garlic powder if using. Blend until smooth.
Meanwhile, add the pasta to the boiling water from Step 1 and cook according to package directions. Drain and return to the pot.
Stir the cheese sauce into the pasta and serve warm, topped with cracked black pepper if desired.
Notes
Store any leftovers in an airtight container in the fridge for 3-5 days. Warm for 30-60 seconds in the microwave to serve.
You can make the cheese sauce up to 3 days ahead and store it in an airtight container. Warm for 15-30 seconds in the microwave before stirring into the pasta.
Use whichever kind of pasta your family likes best.
Omit the garlic powder if you're worried the kids may not like it.
Stir the sauce into the pasta right before serving.
Dairy-free: Omit the cheese, use broth instead of milk, and add 1/2 cup white beans. Or use dairy-free cheese, butter, and milk.