Start by gathering all your ingredients and doing your prep work. Mince the 3 garlic cloves, chop the fresh basil and parsley, and finely grate the parmesan cheese—I always grate parmesan fresh rather than using pre-grated because it blends much more smoothly into the filling. In a medium bowl, combine the ricotta, egg, grated parmesan, fresh basil, parsley, oregano, minced garlic, a pinch of salt, and pepper. Mix until well combined and set aside. Taste the filling and adjust seasonings as needed.

Trim the ends off both zucchini and slice them lengthwise into thin, even strips—about 1/4 inch thick works best for rolling. Arrange the slices on a baking sheet, season generously with salt and pepper on both sides, and roast at 400°F for 8 minutes until they're tender but still hold their shape. Remove from the oven and let cool for a few minutes so they're easier to handle when rolling.

While the zucchini cools, slice the 16 oz mushrooms into thin pieces. Heat 1.5 tbsp olive oil in a large skillet over medium-high heat and add the mushrooms with a pinch of salt and pepper. Cook for 5-7 minutes, stirring occasionally, until the mushrooms are golden and any excess moisture has evaporated. Pour the 3 cups tomato sauce into a 9x13 inch baking dish and stir in the cooked mushrooms and 1/4 tsp red pepper flakes, mixing to combine evenly.

Take each cooled zucchini slice and place a generous spoonful of the ricotta filling from Step 1 near one end, then carefully roll it up tightly and place it seam-side down in the baking dish with the mushroom sauce. I find that arranging the rolls snugly together helps them stay in place and cook evenly. Continue until all zucchini slices and filling are used, nestling the rolls close together in the sauce.

Sprinkle the 1 1/4 cups mozzarella evenly over the top of all the rollups. Bake in a 400°F oven for 10-15 minutes until the cheese is melted and bubbly and the sauce is bubbling around the edges. For extra browning and a slightly crispy cheese top, finish under the broiler for 1 minute, watching carefully to avoid burning. Let cool for 2-3 minutes before serving for easier plating.