Preheat oven to 375.

In a medium pot, combine quinoa and vegetable broth. Bring to a simmer, then reduce heat to low and cover. Cook until broth is absorbed. Remove from heat and let it rest for a few minutes.

Meanwhile, roughly chop the leek. Heat the olive oil in a saute pan over medium heat.

Drain the spinach and use your hands to squeeze excess water out from it. Add the chopped leek to the pan and saute for 2 minutes, then add the spinach and saute for 3 minutes more.

Remove spinach mix from heat and stir in Italian seasoning and salt. Fluff the resting quinoa with a fork, then add to the spinach mixture.

Heat the cream cheese and milk in the microwave in a bowl. Whisk together, then stir into the quinoa mixture. Stir in the cheddar and mozzarella cheeses, and combine everything well.

Coat a 8x11 baking dish with cooking spray. Spread the quinoa mixture evenly into the dish, then sprinkle bread crumbs on top.

Bake in the oven until golden brown, 20-25 minutes.