Step 1: Prepare the Batter

1. Preheat your oven to 375°F (190°C) and grease a 12-cup muffin tin or line it with paper liners.
2. In a large bowl, whisk together flour, baking powder, salt, and black pepper.
3. In another bowl, beat the eggs, milk, and melted butter until well combined. Stir in the Dijon mustard if using.

Step 2: Mix in Cheese and Herbs

1. Add the shredded cheddar, basil, and scallions to the dry ingredients. Toss to coat the cheese and herbs with flour, which helps distribute them evenly.
2. Pour the wet ingredients into the dry mixture and gently fold together until just combined. Do not overmix—a few lumps are okay!

Step 3: Bake the Muffins

1. Spoon the batter evenly into the muffin tin, filling each cup about ¾ full.
2. Bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean.
3. Let the muffins cool in the pan for 5 minutes, then transfer them to a wire rack.

Step 4: Serve and Enjoy!

Enjoy warm with butter, cream cheese, or alongside soups and salads!