Preheat the oven to 400 degrees Fahrenheit.Microwave the zucchini noodles uncovered, on high, for 3 minutes.
Transfer to a colander lined with paper towels and gently squeeze out any moisture from the zoodles.
Set aside.In a large microwave safe bowl, combine the mascarpone cheese, parmesan cheese, Romano cheese, salt, pepper, and nutmeg.
Microwave on high for 1 minute.
Stir.
Microwave on high for 30 more seconds.Remove and whisk together until smooth.Fold in the pesto and mozzarella cheese until fully incorporated.Add the cooked zoodles and stir until well coated.Transfer to a 2 quart casserole dish and bake in the oven for 10 minutes or until the cheese is bubbling at the edges.
Remove and serve immediately.