In a large skillet, heat ½ teaspoon butter. Add onions and garlic and sauté over medium heat until they begin to caramelize, 8-10 minutes.

Add the remaining ½ teaspoon butter to the skillet along with the diced mushrooms and salt. Sauté until the mushrooms begin to sweat and soften, 2-3 minutes.

Add rosemary, thyme, sage, and red pepper flakes. Mix to incorporate.

Pour the wine into the skillet and scrape up any bits of onion that have stuck to the bottom of the pan. Add the tomatoes and mix well. Simmer over medium-low heat, stirring occasionally for 3-5 minutes.

Remove the sauce from the heat and set aside.

In a small bowl mix ricotta, chopped spinach, Parmesan cheese, and beaten egg. Set aside.

Preheat your oven to 350F.

Spread 1 cup of sauce in the bottom of a 9x5 loaf pan (or 8x8 baking dish). Layer ⅓ of the noodles over the sauce and top the noodles with ½ of the cheese mixture. Continue with 1 cup of sauce, ⅓ of the noodles, and the last ½ of the cheese mixture. Finish the layers off with 1 cup of sauce and the last ⅓ of the noodles. Top the noodles with the last 1 cup of sauce.

Cover the dish with aluminum foil and bake for 1- 1 ½ hours, until a knife inserted into the center of the dish slides in smoothly. Remove the foil and top the lasagna with the mozzarella cheese.

Return the dish to the oven and bake, uncovered, until the cheese is melted and golden, 10-15 min.

Remove the lasagna from the oven. Let it stand on the counter, tented loosely with aluminum foil, for 10 minutes before serving.

Serve with a side salad.