Start by slicing your long French baguette into thin, bite-sized pieces, aiming for 28-32 slices.

Spread a layer of mayonnaise or melted butter on one side of each baguette slice. Lay half the slices face down on a clean surface. Spread pesto on each followed by shredded white cheddar cheese. Sprinkle with salt and pepper, then top with remaining slices, mayo-side up.

Heat a large non-stick pan over medium heat for about 5 minutes. Place the assembled sandwiches in the pan, ensuring not to overcrowd. Cook each side for 3-4 minutes until golden brown and crispy.

Carefully remove sandwiches from the pan and place them on a serving platter. Serve hot as an appetizer or alongside your favorite soup.