01 - Preheat oven to 375°F. Lightly grease four individual ramekins or a medium baking dish.
02 - Melt butter in a saucepan over medium heat. Whisk in flour and cook for 1 minute. Gradually add milk, whisking constantly until thickened. Stir in Gruyère cheese, nutmeg, salt, and pepper. Remove from heat.
03 - Sauté spinach in a skillet until just wilted, about 2-3 minutes.
04 - Place a puff pastry slice or toasted brioche in the bottom of each ramekin. Layer with sautéed spinach, zucchini slices, tomato, and ham.
05 - Spoon cheese sauce over the layered ingredients. Create a shallow well in the center of each and crack an egg on top. Season eggs lightly with salt and pepper.
06 - Bake for 20-25 minutes until egg whites are set but yolks remain runny. Adjust time for firmer yolks if preferred.
07 - Remove from oven and garnish with fresh chives or parsley. Serve immediately.