Beat eggs, adding salt and pepper. Fry bacon until almost crisp, draining any excess fat. Add onion and celery. Fry for additional 3 minutes, stirring often. Drain any fat. Set aside to cool. Add eggs to cooled mixture, followed by cheese, then Ritz crackers. Grease mini muffin tins well. Fill each muffin tin well to the top. Bake at 375°F for 15 - 20 minutes. Let sit in muffin tins for 2 minutes before removing. These are excellent frozen. Reheat in microwave or oven to serve.