Prepare pasta according to package directions, using a very large pot. Add the broccoli for the last 3 minutes of cooking. Reserve 1/2 cup of the pasta cooking water.
Drain the pasta and broccoli in a colander. Return to the pot. Toss with the butter.
Meanwhile, add the ricotta, lemon zest, lemon juice, salt, Parmesan cheese, and 1/4 cup cold water to blender. Blend smooth.
Add the cheese mixture to the pot with the pasta and broccoli. Use a spatula to toss the pasta until coated, adding a little of the reserved pasta water at a time until a smooth, but thick sauce forms.
Transfer pasta to a large bowl and top with additional cheese to serve—if desired.
Store any leftovers in an airtight container for up to 5 days. Reheat to serve, stirring in a little of the reserved pasta water, regular water, or broth if needed.
Notes
Store leftover pasta in an airtight container in the fridge for up to 5 days. Reheat in a heat-safe bowl or plate to serve.
Ladle out some of the pasta water before you drain so you have it set aside and ready to use.
Use whichever type of pasta your family prefers.
If using gluten-free pasta, you can use stock or broth instead of pasta water to smooth out the sauce.
Save any remaining pasta cooking water to add moisture when reheating the pasta.
To use frozen broccoli instead of fresh, add it to the pasta cooking pot for just the final minute of cooking.
This does taste lemony so you may want to reduce the amount of lemon juice slightly if that flavor is new to your kids.
Use cottage cheese instead of ricotta if preferred.