Frittata with Spinach, Potatoes, and Leeks

Prepare the leek mixture and prepare the potatoes for the day ahead. Or use store-bought boiled potatoes, cut into cubes (for example, just potatoes), beat the eggs, mix everything together and bake in the morning before brunch.
Preheat the oven to 350 degrees.Melt the butter in a roasting pan over medium-high heat. Add the leeks; simmer for 4 minutes. Add the spinach; simmer for 2 minutes or until the spinach wilts. Drain the mixture in a colander, squeezing until it is barely moist.Combine the milk, basil, salt, pepper, eggs, and egg whites; whisk well. Add the leek and potato mixture. Place in a 10-inch round ceramic baking dish or pie dish greased with cooking spray. Sprinkle with breadcrumbs and sprinkle with cheese. Bake at 350 ° C for 25 minutes or until the center is set.Preheat the grill.Bake the frittata for 4 minutes or until golden brown. Cut into slices.