Preheat the oven to 375 degrees.
Cook the ground chicken over medium heat on the stovetop for approximately 5 minutes, until no pink remains and it's cooked through. Set aside.
Saute the spinach and garlic together for 3-4 minutes to soften. It should be vibrant and green, not browned.
In a large mixing bowl, add the eggs and milk together and whisk until combined.
Then stir in all other ingredients, including the cooked ground chicken and sautee d spinach.
Pour into a greased pie pan.
Cook for 60-70 minutes until frittata is completely set and does not jiggle in the middle. Check every few minutes after 60.