Preheat the oven to 375 degrees F. Grease 4 (6 oz) ramekins with nonstick cooking spray and set aside.
In a large skillet, heat the olive oil over medium high heat. Add the shallot and garlic and cook for 2-3 minutes. Stir in the spinach and cook until wilted, about 5 minutes.
Divide the cooked spinach among the prepared ramekins. Break an egg into each ramekin and sprinkle each with salt and black pepper, to taste. Place the ramekins on a rimmed baking sheet.
Bake until the whites are set and the yolks are firm around the edges but still soft in the center, about 15 to 20 minutes. Remove from the oven and garnish with tomatoes, avocado, and feta cheese. Serve immediately. We like to serve the baked eggs with toast.