Grilled Onion Frittata

Description
This recipe came from an estate sale. I obtained it when I purchased the family collection from the Clark Estate in Flower Mound, Texas in 1982.
 * Contributed by Catsrecipes Y-Group

Ingredients

 * 1 red onion peeled and cut into 8 wedges
 * 1 yellow onion peeled and cut into 8 wedges
 * ½ teaspoon salt
 * 1 teaspoon freshly ground black pepper
 * olive oil as needed
 * 10 large eggs
 * ¼ cup heavy cream
 * ½ cup freshly grated Parmesan cheese
 * 2 tablespoons unsalted butter
 * 1 teaspoon finely chopped fresh rosemary

Directions

 * 1) Preheat oven to 350°F.
 * 2) In large bowl combine red and yellow onions, salt, pepper and olive oil and toss to coat well.
 * 3) Preheat grill pan over high heat.
 * 4) Arrange onion wedges on pan and cook until browned and tender underneath about 5 minutes.
 * 5) Turn and cook until onions are very tender about 7 minutes more.
 * 6) Transfer to a plate and set aside.
 * 7) In large bowl whisk eggs and cream until blended.
 * 8) Stir in cheese, salt and pepper until smooth.
 * 9) In medium skillet melt butter over medium heat then add rosemary and cook 1 minute.
 * 10) Pour egg mixture into pan and fold gently to combine the rosemary and eggs.
 * 11) Arrange the grilled onions on top then transfer pan to the oven and bake 15 minutes.