Cook pasta according to package directions, omitting the salt and fat. Drain well.
Steam Brussels sprouts, covered, 7 minutes or until tender. Drain and sprinkle with salt.
Cook bacon in a Dutch oven over medium-high heat until crisp. Remove bacon from pan, reserving 1 teaspoon drippings in pan. Crumble bacon; set aside.
Add Brussels sprouts to the bacon drippings in pan; sauté 5 minutes or until lightly browned. Stir in cooked pasta; cover mixture, and keep warm.
Combine milk, flour, and broth, stirring well with a whisk. Melt butter in a medium saucepan over medium heat. Gradually add milk mixture, stirring constantly with a whisk until well blended. Cook for 6 minutes or until thickened, stirring constantly. Stir in 1/4 cup cheese, stirring until cheese melts. Pour sauce over pasta mixture, tossing to coat. Top with remaining 1/2 cup cheese, nuts, bacon, and pepper; serve immediately.