Preheat oven to 400 degrees.
Finely chop onion. Heat olive oil in skillet and saute for 6 minutes.
Add the mushrooms and saute for 4 minutes.
While onion and mushrooms are cooking put zucchini and squash into food processor to shred (or manually shred on largest hole on grater).
Add the zucchini and squash to the skillet and saute for 5 minutes. If there is still liquid left after cooking, drain.
Stir in two thirds of the ricotta, all of the mascarpone, 1/3 cup of the Parmesan, and 2 tablespoons of the herbs. Mix with all the veggies until fully incorporated.