In skillet heat oil over medium heat cook white parts of onion stirring for 2 minutes, add mushrooms, red pepper and paprika and S and P, cook stirring occasionally until very little liquid remains and mushrooms are golden about 6 minutes. Add spinach and cook just until spinach is wilted,,remove from heat and add green part of onion stir until well combined and divide into 12 greased muffin cups...set aside.
In bowl beat eggs and milk, divide into 12 muffin cups, sprinkle with feta cheese. Bake in 350F oven until edges are set about 10 to 12 minutes..Broil until puffed and golden about 2 minutes watching not to burn.
Remove from oven let cool in pan then remove to wire rack to cool serve warm...These can be kept in the refrigerator for up to 3 days or frozen individually wrapped in foil and reheated to serve.