Heat the olive oil in a large, deep skillet or Dutch oven over medium-high heat until shimmering.
Add the sausage and break it into bite-sized pieces with a wooden spoon, cooking for 5-7 minutes until browned and cooked through.
Add the garlic, red pepper flakes, and fennel seeds (if using), stirring constantly for 30 seconds until fragrant.
Pour in the chicken broth, water, salt, and pepper, then bring the mixture to a boil.
Add the orecchiette pasta, stirring well to prevent sticking, and reduce heat to maintain a steady simmer.
Cook for 8 minutes, stirring occasionally to ensure even cooking.
Add the broccoli florets, nestling them into the pasta, and continue cooking for 4-5 minutes until the broccoli is tender and the pasta is al dente.
Reduce heat to low and stir in the heavy cream, Parmesan cheese, and butter until the sauce becomes creamy and coats the pasta.
Add the cherry tomatoes if using, allowing them to warm through for 1-2 minutes.
Taste and adjust seasoning with additional salt, pepper, or red pepper flakes as needed.
Serve immediately topped with extra Parmesan, fresh basil, and a sprinkle of lemon zest if desired.