Preheat the oven to 375 degrees. Slice each squash in half and scoop out the seeds. Place on a baking sheet and drizzle about a teaspoon of olive oil in each half, then season with salt and pepper.
Bake at 375 degrees for about 30 minutes.
While the squash cooks, prepare the filling. In a skillet, cook the onion and ground turkey or beef over medium heat. Cook until meat is no longer pink.
Drain off any oil, then add the garlic powder, salt, pepper, and tomatoes. Cook on low for a few minutes to allow the flavors to blend.
Once the squash is tender, remove from the oven and spoon the stuffing into each half. Return to the oven and bake for about 10 minutes.