Cook the Pasta: Cook Store-bought Tortellini in a large pot of boiling salted water, stirring occasionally, until very al dente, about 1 minute less than package directions.
Sauté the Fennel: In a large skillet, melt the butter over medium heat. Add the Fennel. Sauté and caramelize, add white wine and cover with lid until soft and fragrant for about 1 minute. Season with salt. Remove the cooked fennel to a plate, and set aside.
Sausage: Add sausage to same pot and cook, breaking up and stirring occasionally, until browned and cooked through, 6–8 minutes. Add butter, garlic and Sauté.
Fennel/Tortellini: Transfer fennel to skillet with sausage and 1/2 cup pasta cooking liquid. Add cooked Tortellini tossing often, until pasta is al dente, and sauce is thickened, for about 2 minutes.
Cheese: Add 1/4 cup cheese, tossing until melted. Thin with more pasta cooking liquid if needed. Season with pepper, and more salt if needed.