Trim bottom half inch from broccolini stems and cut larger pieces lengthwise in half.
Bring a large pot of salty water to a boil. Cook casarecce pasta according to package directions, 2 minutes shy of al dente.
Add broccolini to pasta in boiling water and cook for one minute until bright green and tender crisp.
Reserve a few cups of pasta water and drain pasta and broccolini.
Return pot to the heat on medium high and add olive oil. Add in ground Italian sausage and cook until browned and cooked through.
Add in minced garlic and cook for 1 minute until fragrant. Deglaze the pan with white wine and cook for an additional minute. (see note for omitting wine)
Turn the heat down to medium low and add the casarecce and broccolini back into the pot. Stir in cheese and lemon zest and one cup of reserved pasta water.
Add ½ cup to one full cup of pasta water a little at a time until the pasta is coated in a light and glossy sauce, cooking for an additional 1-2 minutes.
Serve in big bowls topped with more cheese and crushed red pepper flakes.