cook tortellini and drain
while the tortellini is cooking, in a large skillet - melt part of the butter - saute the mushrooms along with garlic powder, onion powder, salt and pepper
remove the mushroom mixture from the skillet and place it in a large bowl
in the skillet, add milk and the rest of the butter
bring to a slight boil
add the parmesan cheese and stir until smooth
to the bowl of mushrooms add the drained tortellini, spinach, and cheese sauce
toss the mixture until it is all mixed together
transfer the mixture to a 3-quart baking dish and sprinkle with mozzarella cheese
bake, covered at 350 degrees for 15 minutes
uncover the dish and bake for another 10 minutes