Place the squash halves faced down on a baking sheet and add about 1/2 inch of water to the baking sheet. Bake at 375 degrees for 40 minutes. Remove from the oven and let the squash cool for 10 minutes.
In a large skillet melt the butter on high heat. Next, add in the garlic and sauté until golden, about 1-2 minutes.
Next, add in the onion and sauté for 2 minutes, mixing occasionally.
After the squash has cooled for 10 minutes, pull the squash from the skin using a fork. Add in the cooked squash, salt, and pepper, to the skillet and sauté for 5 minutes, mixing occasionally.