Mustard Macaroni and Cheese

Ingredients (10)

• ✓ ½ (8 ounce) package Cheddar cheese, or to taste
• + 4 slices back bacon add to pantry
• + 1 (8 ounce) package elbow macaroni add to pantry
• ✓ 1 tablespoon butter
• + 1 tablespoon all-purpose flour add to pantry
• + 1 pint milk add to pantry
• + 2 teaspoons Dijon mustard (such as Maille Dijon Originale®) add to pantry
• + salt and freshly ground black pepper to taste add to pantry
• + salt and freshly ground black pepper to taste add to pantry
• ✓ 1 leek, trimmed and cut into thin rings