Preheat oven to 400˚F. 

Generously coat 12 muffin cups with cooking spray. 

In a small skillet, heat olive oil over medium heat. Add onions. Saute until soft, about 3 to 5 minutes.  

Place the cottage cheese in a food processor. Blend until smooth, about 45 seconds to one minute.  Reserve. Place eggs in large mixing bowl and whisk until just beaten.  Add the cottage cheese, onions, spinach, cheddar cheese, and black pepper to the eggs.  Mix well.

Divide the spinach mixture evenly among the 12 muffin cups.  Bake until the spinach cups are firm, about  20 minutes.  Remove from the oven and place on wire cooling rack. Let stand in pan for about 5 minutes. To remove, loosen the edges with a knife and lift out with a fork. Allow to cool for another 5 minutes on wire cooling rack. Serve warm or cold.