Prosciutto Egg Cups - cooking recipe

Ingredients

1 onion, thinly sliced
1 tablespoon brown sugar
2 drops white wine vinegar
cooking spray
4 egg whites
2 eggs
1/4 cup shredded Gouda cheese
1 slice thick-cut prosciutto, cubed

Preparation

Cook and stir onion, brown sugar, and vinegar in a skillet over medium heat until onion is golden, about 20 minutes.
Preheat oven to 350 degrees F (175 degrees C). Spray a 6-muffin tin with cooking spray.
Whisk egg whites and eggs in a large measuring cup.
Fill each muffin cup halfway with egg mixture. Scatter onion, Gouda cheese, and prosciutto cubes on top. Cover with remaining egg mixture, leaving 1/4-inch space at the top for eggs to rise.
Bake in the preheated oven until golden brown on top, about 20 minutes.