Bring a large pot of heavily salted water to a boil. Add the Pastariso Gluten Free Brown Rice Vegetable Rotini and cook for 6 – 7 minutes. Drain and rinse with hot water.
While the pasta is cooking heat 2 tablespoons of olive oil in a large pot or Dutch oven over medium high heat. Add the onions and cook until they are softened and translucent, about 5 minutes. Add ½ teaspoon of salt, ¼ teaspoon pepper and stir in the flour. Cook, stirring constantly, for 1 minute. Add the chicken broth and milk, raise the heat and bring to a boil. Reduce heat and cook until the sauce thickens, 6 – 8 minutes. Stir in the tuna, peas and cooked pasta. Pour the mixture into a 9- by 13-inch baking dish.
Combine the remaining tablespoon of olive oil with the panko bread crumbs and top the tuna mixture. Bake for 15 – 20 minutes or until the top is browned and the sauce bubbly. Let cool a few minutes before serving.