Created by TexanerinCook on June 17, 2014
Step 1: Pulse bread in a food processor until coarsely ground (you should have 1 cup). Toast breadcrumbs in a large skillet over medium heat, tossing, until golden and crisp, about 7 minutes. Remove from heat and add butter, tossing to coat, then mix in 1/4 cup Parmesan cheese.
Step 2: Cook pasta in a large pot of generously salted water until al dente, according to package directions. Reserve 1 cup pasta water; drain.
Step 3: Meanwhile, whisk together eggs, cream, and mustard in a bowl. Mix in 1/2 cup Parmesan cheese and 1/2 cup cheddar cheese,
Step 4: Return pasta to pot and add egg mixture. Cook over low heat, stirring, until sauce has thickened, about 2 minutes. Add reserved pasta water, 1/4 cup at a time, until pasta is evenly coated.
Step 5: Season with salt and pepper. Serve immediately, topped with breadcrumb-Parmesan mixture.