2 tablespoons olive oil, divided
1 pound uncooked spicy Italian sausage, casings removed
2 large fennel bulbs, trimmed, cored, and thinly sliced (reserve 1/4 cup chopped fronds for serving)
1 pound dry orecchiette pasta
Freshly ground black pepper
Freshly grated Parmesan cheese, for serving
Heat 1 tablespoon of the oil in a large skillet over medium-high heat until shimmering. Add the sausage and cook, breaking it up with a wooden spoon, until browned and cooked through, about 10 minutes. Transfer to a paper towel-lined plate and drain any excess fat in the pan.
Add the remaining 1 tablespoon oil and sliced fennel to the pan. Reduce the heat to medium and cook, stirring frequently and reducing the heat if the fennel starts to burn, until the fennel is soft and caramelized, 15 to 20 minutes. Season with salt and pepper as needed. Meanwhile, bring a large pot of salted water to a boil.
Add the pasta to the boiling water and cook until al dente, 8 to 10 minutes, or according to package instructions. Reserve 1/2 cup of the cooking water, then drain.
Add the cooked sausage, pasta, and the reserved pasta water to the skillet, tossing to combine. Continue to toss and stir the pasta until the sauce coats the pasta and the water has evaporated, 2 to 3 minutes.
Serve with Parmesan cheese and the reserved fennel fronds sprinkled over the top of each bowl.