Egg and Croissant Brunch Bake

Heat olive oil in a skillet over medium-low heat. Add the thinly sliced onion and cook, stirring occasionally, for about 30 minutes until deep golden brown and jammy.

In a separate skillet, brown the diced ham in a little olive oil until the edges are crispy. Add the baby spinach and stir until just wilted. Remove from heat.

In a large bowl, whisk together the eggs, milk, Dijon mustard, salt, and pepper until well combined.

Preheat the oven to 350 degrees F. Grease a 9x13-inch baking dish. Layer the ham, spinach, and caramelized onions in the dish. Sprinkle half the shredded cheese over the top. Pour the egg mixture evenly over the layers. Arrange torn croissant pieces on the surface and sprinkle the remaining cheese on top.

Cover the dish with foil and bake for 30 minutes. Remove the foil and bake for an additional 5 to 10 minutes until the eggs are nearly set and the croissants are golden. Let rest briefly before slicing.