In a 4-quart Dutch oven or large saucepan cook pasta according to package directions. Drain pasta. Return to the same pan; cover and keep warm.
Meanwhile, trim fennel, reserving feathery leaves for garnish, if desired. Cut fennel bulbs crosswise into thin strips.
In a medium skillet cook garlic and crushed red pepper in oil and margarine or butter for 30 seconds. Add fennel to skillet; cook and stir for 5 minutes. Add sweet pepper strips; cook 3 minutes more. Add beans and thyme; cook 2 minutes to heat through. Add fennel mixture to pasta; toss gently. Season to taste with cracked black pepper. Sprinkle with Parmesan cheese. Makes 4 servings.