Mediterranean-style Spinach

My husband often accuses me of turning every dish I make into the Italian flag.  He's right; if a dish is missing green, white or red, I always find a way to add it.  When I first made this dish, I used black pepper.  When I looked at it, I thought it needed more color, so I used red pepper flakes instead - once again, the Italian flag! 

1 tbsp olive oil
2-3 cloves garlic, minced
1 pound frozen chopped spinach, thawed and drained
2 large yellow onions, diced
4 ounces feta cheese*, diced
Celtic sea salt
red pepper flakes

Heat oil and sauté garlic and onions until translucent.  Add spinach and feta and mix until spinach is warm and cheese has softened.  Season with salt and a pinch of red pepper flakes.

*Feta cheese should not be made from cow's milk - find a high-quality feta made from sheep and/or goat's milk.