Preheat oven to 375F
Brown the sausage in a pan over med-high heat.
Spray a 9x13" pan.
Whisk the eggs, add the milk, salt&pepper, then whisk some more.
Add browned sausage to pan.
Add the spinach and feta.
Pour egg mixture on top.
Bake for 20-25 minutes (toothpick test).