Follow these simple steps to create the amazing Killer Maple Mustard Croissant Breakfast Sandwiches:

1. Prepare the Croissants: Preheat your oven to 350°F (175°C). Slice the croissants in half horizontally without completely separating the halves.
2. Cook the Eggs: In a non-stick skillet, melt a small amount of butter over medium heat. Crack the eggs into the skillet, seasoning with salt and pepper. Cook until the eggs are set, but still soft.
3. Prepare the Maple Mustard Sauce: In a small bowl, combine the Dijon mustard and maple syrup. Mix thoroughly until well-blended.
4. Assemble the Sandwiches: Spread a tablespoon of the maple mustard sauce on each croissant half. If using, layer the cooked bacon and fresh spinach on the bottom half.
5. Add the Eggs: Place a cooked egg on top of the bacon and spinach layer.
6. Top and Finish: Close the sandwiches with the other half of the croissant. Place them on a baking sheet.
7. Heat in Oven: Bake the assembled sandwiches in the preheated oven for about 5 minutes, just until warmed through and slightly crispy.
8. Serve Immediately: Remove from the oven and let cool slightly before serving.

These straightforward steps will ensure your breakfast sandwiches come out perfectly every time!