Mac and Cheese and Beer

INGREDIENTS

• 3 sourdough pretzels, crushed
• 2 tablespoons grated Parmesan cheese
• 1 (16 ounce) package whole wheat elbow macaroni
• 6 slices bacon, chopped
• 1 tablespoon butter
• 1 onion, diced
• 2 stalks celery, diced
• 2 carrots, diced
• 2 cloves garlic, minced
• 3 tablespoons all-purpose flour
• 2 tablespoons Dijon mustard
• 1 (12 fluid ounce) bottle beer
• 2 1/2 cups milk
• 3 cups shredded sharp Cheddar cheese
• 1/2 teaspoon ground red pepper
• salt and pepper, to taste