Place the drained and rinsed chickpeas in an ovenproof skillet along with the chopped onion, avocado oil, chili powder, and salt.
Sauté on medium-high for about 15 – 20 minutes, stirring frequently until the chickpeas and onions get golden brown.
Really take the time with the onions and chickpeas to make sure they’re perfect. This is the base of the frittata and gives it tons of flavor so sauté away until they look golden brown and almost crispy to you!
In the last few minutes of sautéing, add in the minced garlic and continue to cook until fragrant.
Remove from heat.
Add the spinach to the hot pan (removed from heat) and stir until slightly wilted.
In a medium bowl, whisk together the eggs and milk.
Pour the egg/milk mixture into the pan, using a spatula to evenly distribute the chickpeas.
Sprinkle the top of the frittata with the feta and place in the oven for 15 minutes until the edges puff up and the center is set.