Bring a large pot of heavily salted water to a boil. Cook the pasta until al dente according to package directions. Reserve 1 cup pasta water, drain and return the pasta to the pot, covered.
Place marinara sauce, cottage cheese, parmesan cheese, melted butter, crushed red pepper and pasta water in a high speed blender and blend until smooth and creamy, 1-2 minutes.
Transfer the sauce on top of the cooked pasta and toss until combined and heated through. Serve immediately with more red pepper flakes and chopped parsley, if desired.
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Notes
Storage: Allow the pasta to cook and store in an airtight container in the fridge up to 4 days. Reheat on the stove with a splash of water or broth until heated through. Tips:Add pasta water to your sauce. The starches in the pasta water when blended with cottage cheese creates a smooth sauce that is less likely to break down.Use any cottage cheese. Whole milk cottage cheese will be much more flavorful and add richness to your pasta. If you're making blended cottage cheese pasta sauce for the protein punch, you're in luck because both low fat and full fat cottage cheese has about the same amount in each serving.Add veggies. Just like most pasta dishes, adding more vegetables can really bulk up your meal! Try adding spinach, zucchini, mushrooms, or any other veggies to your protein pasta sauce!