Preheat the oven to 350˚ F. Lightly grease a 2 quart baking dish. In a large skillet over medium heat sauté the mushrooms in the olive oil, stirring occasionally, until the mushrooms have released most of their liquid, about 5-7 minutes. Add the onions to the pan and cook, stirring occasionally, until translucent and tender, about 4-5 minutes. Stir in the garlic and cook just until fragrant, about 1 minute. Remove from the heat. Add the rice to the skillet and stir to combine.
In a large bowl, whisk together the eggs, cottage cheese, sour cream, and salt until smooth. Add in the rice mixture and stir gently until well blended. Sprinkle most of the Parmesan over the top, reserving a bit for finishing. Cover the dish with foil and bake for 30 minutes. Remove the foil and bake for 20-30 minutes more, until the top is lightly browned. Top with remaining Parmesan and fresh herbs, if desired.