Puncture spaghetti squash 4-5 times with a fork. Place in microwave for 4 minutes. Once cool, cut the squash in half. Scoop out the seeds then place cut side down on a baking tray lined with a silpat or parchment paper.
Bake for 1 hour in a 400 degree oven. Remove for oven and let cool.
While the spaghetti squash is cooking prepare oil-free pesto.
Remove spaghetti squash from the shell and mix with pesto in a separate bowl. Replace the mixture in the shells.
In a medium pan, saute mushrooms and tomatoes with balsamic vinegar to taste.
Top the spaghetti squash with tomato and mushroom mixture and then place in the oven at 350 degrees for 15-20 minutes or until heated through.
