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