Cook fettucine in a large pot of salted boiling water according to package instructions. Reserve ½ cup pasta water before draining.
Blend the cottage cheese, milk, parmesan, cornstarch, Italian seasoning, garlic powder, salt, and pepper until completely smooth.
Transfer the sauce to a large skillet over medium heat. Cook 8–10 minutes, whisking frequently, until thickened.
Add the drained pasta and toss to coat. Add pasta water as needed to thin. Serve immediately with fresh parsley and red pepper flakes.