In a small saucepan over low heat, combine 2 tablespoons of maple syrup and 1 tablespoon of Dijon mustard. Whisk together until thickened, about 3 minutes.

Lay 8 slices of bacon in a cold skillet and turn the heat to medium. Cook until crisp and golden, about 10 minutes, turning once.

Crack 4 eggs into a bowl, season with salt and pepper, and whisk. In a nonstick skillet, heat 1 tablespoon of butter and scramble the eggs gently for about 2 minutes.

Slice croissants horizontally and optionally spread butter on cut sides. Toast them cut side down in a skillet over medium heat for about 2 minutes.

Spread a layer of maple mustard sauce on the bottom half of each toasted croissant, then layer with 2 slices of crispy bacon, scrambled eggs, and cheddar cheese. Top with the other half of the croissant.

Preheat oven to 350°F (175°C). Place the assembled sandwiches on a baking sheet and warm in the oven for about 5 minutes, until cheese is melted.