Preheat oven to 350 degrees F.
In a small skillet, heat olive oil. Add garlic and sauté for 1 minute, until fragrant. Add minced onions and sauté until softened, about 5 minutes.
Add thawed spinach (make sure to wring out all excess water!) to skillet and stir well to break up any large pieces of spinach.
Add feta, cream cheese, egg, nutmeg, salt and pepper. Stir well until mixture is well combined.
On a baking sheet, add mini phyllo cups. Add a heaping tablespoon of mixture into each tart.
Place in oven and bake for 10 -12 minutes, until mixture is heated through. Serve immediately.