Preheat the oven to 375 degrees.
Brown the sausage in a pan over medium-high heat.
Spray or coat a 9 x 13" pan in the oil.
Crack and whisk the dozen eggs in a separate bowl.
Add the milk to the eggs and whisk again.
Once the sausage is browned, add to the pan.
Top with the chopped spinach and feta.
Pour the egg mixture over the top.
Season with salt and pepper.
Bake for 20-25 minutes or until a fork comes out clean.
Enjoy!