Step 1: Make the Maple Mustard Sauce

1. In a small bowl, whisk together Dijon mustard, maple syrup, and mayonnaise until smooth. Set aside. This sweet-tangy sauce will tie the sandwich together perfectly.

Step 2: Prepare the Eggs

1. Crack the eggs into a bowl, add the milk, and whisk until fully combined. Add a pinch of salt and pepper.
2. Heat a nonstick skillet over medium-low heat and melt the butter. Pour in the egg mixture and cook gently, stirring frequently, until soft curds form and the eggs are just set but still creamy. Remove from heat.

Step 3: Assemble the Sandwiches

1. Spread a generous layer of the maple mustard sauce on the bottom half of each croissant.
2. Layer a slice of cheddar cheese on top of the sauce.
3. Divide the scrambled eggs evenly among the croissants, placing them over the cheese.
4. Add a slice of crispy turkey bacon on top of the eggs.
5. If using, layer a small handful of baby spinach for freshness and color.
6. Place the top half of the croissant over the filling to complete the sandwich.

Step 4: Warm the Sandwiches

1. Preheat a skillet or pan over medium heat. Place the assembled sandwiches in the skillet, pressing down lightly. Cover with a lid to help the cheese melt. Heat for 1–2 minutes per side, until the croissants are warm and slightly crispy, and the cheese has melted.

Step 5: Serve

1. Serve the croissant breakfast sandwiches warm, with extra maple mustard sauce on the side for dipping if desired. Enjoy!