Spinach and Caramelized Onion Strata

1. Heat oil in a 10-inch skillet over medium heat. Meanwhile, peel and coarsely chop the onions, adding them to the skillet as you chop. Cook, stirring occasionally over medium heat until soft and caramelized, about 7 minutes. While the onions are cooking, place the spinach on a microwave safe plate and cook on high for 3 minutes, or until thawed well. Place defrosted spinach in a colander and press to remove as much water as possible. Leave to drain.

2. In a large bowl, crack the eggs and add the milk and 1 cup of the cheese. Add the drained spinach. Whisk to mix well.

3. Spray a 13-by-9-inch glass casserole dish with cooking-oil spray. Cut the bread into 1-inch cubes and place them in the dish. When the onions are caramelized, toss them with the bread cubes, making sure to combine well. Slowly pour the egg mixture over the breadmixture, making sure they are completely soaked. Sprinkle the remaining cheese over casserole, add salt and pepper, and cover tightly with plastic wrap. Refrigerate for at least 4 hours or overnight.

4. Preheat the oven to 350° degrees. Bake the casserole for 1 hour or until hot and bubbling along the edges. Remove from the oven and let rest 5 minutes. Cut into squares and serve.