Cook shells following package directions. Add peas for last 1 minute.
Meanwhile, melt butter in medium-size heavy-bottomed saucepan over medium heat. Add flour; cook 2 minutes, whisking until smooth. Whisk in 1 cup milk. Gradually whisk in remaining milk, 1 cup at a time, until smooth. Stir in salt, nutmeg and cayenne. Bring to a boil. Reduce heat; simmer, whisking, 2 minutes, until thickened. Remove from heat. Stir in cheese.
Drain pasta, peas; return to pot. Add cheese sauce. Top with bacon. Makes 8 servings.
