1. Preheat your oven to 350°F (175°C). Slice the croissants in half horizontally and place them cut side up on a baking sheet. Warm them in the oven for about 5 minutes to get them slightly crisp and buttery.
2. While the croissants warm, cook the bacon in a skillet over medium heat until crispy, about 6-8 minutes. Remove and drain on paper towels.
3. In the same skillet, melt the butter over medium heat. Crack the eggs into the pan, seasoning with salt and pepper. For a classic sandwich, fry the eggs sunny side up or over easy so the yolk stays runny. If you prefer, scramble them lightly—just don’t overcook! This step usually takes 3-4 minutes.
4. Once eggs are almost done, place a slice of cheese on top so it melts gently from the residual heat.
5. Remove croissants from the oven and, if desired, spread mayonnaise or Dijon mustard on the cut sides for extra flavor.
6. Start assembling: layer the bottom half with bacon (or your chosen protein), then the cheesy egg, and if you’re adding greens or tomato slices, pop those on next.
7. Top with the other half of the croissant, press gently, and serve immediately.

From personal experience, timing is everything here. I’ve learned the hard way that if you let the croissants sit too long after warming, they lose that beautiful crispness. And cooking the eggs just right—whether you like runny yolks or fully set—is what makes or breaks the sandwich for everyone at my table.