Heat the oil in a very large skillet (large enough to comfortably hold all of the sauce ingredients) over medium-low heat. Add the onion and ½ teaspoon salt, cover and cook until softened, about 8-10 minutes.

Stir in the garlic, tomato paste, and red pepper flakes and cook for about 30 more seconds. Stir in half of the ground turkey and crumble and cook until the meat is no longer pink, but not browned - about 4 minutes. Add the crushed tomatoes and diced tomatoes (with juices), chicken broth, and bay leaves. Bring to a simmer and cook, stirring occasionally, for about 45 minutes, until sauce is thickened.

Stir the remaining turkey into the sauce and continue to simmer, stirring occasionally, for 25 more minutes. Turn off the heat, remove the bay leaves, stir in the basil, and add salt & pepper to taste.

Preheat the oven to 375 with an oven rack in the middle position. Mix the ricotta, 8 oz (about 2 cups) of the mozzarella, 1 oz (½ cup) of the Parmesan, egg, and ½ teaspoon each salt & pepper together in a large bowl until thoroughly combined.

Spray a 9x13 pan with nonstick spray. Spread 1 ½ cups of meat sauce evenly over the bottom of the dish.

Lay 3 lasagna noodles spaced evenly apart on top of the sauce. Don't worry if there seems to be extra room around the noodles, they expand a little while baking. Add ⅓ cup of cheese filling on top of each noodle and spread it out evenly with a spatula or the back of a spoon. Add 1 more cup of meat sauce and spread evenly. Repeat the noodle/cheese/meat sauce layering 2 more times (you will have used 9 of your 12 noodles at this point.)

Lay the remaining 3 noodles on top and spread the remaining sauce (there should be about 1 ½ cups left) over the noodles, making sure to cover the edges. (You want to cover the edges because if they bake without sauce over the top, they get very tough and chewy.) Cover the lasagna tightly with foil.

Place the dish of lasagna on a rimmed baking sheet and bake for 45 minutes. (As I mentioned, the noodles expand a little while baking so using the rimmed baking sheet helps prevent spillage on the bottom of your oven - odds are it won't spill over, but if it does you'll be very glad you did this! If it doesn't, pan is still clean - win-win!)

Remove the foil and sprinkle the remaining 4 oz (1 cup) of mozzarella and ¼ oz (2 Tbsp) of Parmesan over the top. Bake uncovered until the cheese is melted and slightly bubbly/brown, another 10-15 minutes. If you want the cheese to be extra browned, pop it under the broiler for a minute or two, but really keep an eye on it...broilers move fast!

Remove from oven and allow to cool at least 15 minutes before serving to let the lasagna set up. (I know it's hard but be patient - if you cut into it right away, you'll have a soupy mess!) Enjoy with a green salad and/or garlic bread!