Preheat oven to 400˚F.
Line a baking sheet with parchment paper or foil.
Scoop out the seeds and stringy center from the squash and discard.
Place squash cut side up on the baking sheet. Brush with olive oil and sprinkle with salt and pepper; then turn them over, cut-sides down.
Bake for 35 to 40 minutes, or until tender.
Let squash cool slightly, or until cool enough to handle.
Using a fork, shred the spaghetti squash while leaving about a 1/4-inch border around the sides. Transfer spaghetti squash strings to a large bowl.
Transfer unfilled boats back to the baking sheet and set aside.
To the squash strings add the shredded chicken and zucchini.
Season chicken mixture with cumin, chili powder, oregano, salt, and pepper.
Stir in 1 cup red enchilada sauce.
Divide the chicken mixture between the two squash shells.
Top with remaining enchilada sauce and then top with the cheese.
Bake for 10 minutes, or until cheese is melted.
To get a bit of browning on top, turn on the broiler and continue to cook for 2 more minutes, or until top is browned.
Remove from oven.
Garnish with cilantro.
Cut each shell in half and serve.