Preheat the oven to 350 degrees F (175 degrees C). Line a baking sheet with aluminum foil.

Place 1 acorn squash half onto the prepared baking sheet; drizzle with 1/2 tablespoon oil and season with salt. Wrap and refrigerate other squash half for another use.

Bake squash in the preheated oven until tender and easily pierced with a fork, about 40 minutes.

Spray a frying pan lightly with cooking spray. Place bacon into the pan and cook over medium-high heat, turning occasionally, until crisp, about 10 minutes. Drain bacon slices on paper towels. When cool enough to handle, cut into small pieces and set aside.

Heat remaining 1/2 tablespoon oil in the same pan over medium heat. Cook mushrooms, onion, and garlic in the hot oil until tender, 5 to 7 minutes. Add bread cubes, water, sage, thyme, salt, and pepper. Continue to cook until desired consistency is achieved, 5 to 7 minutes more. Add bacon, mix, and set aside.

Remove squash from the oven and carefully scoop contents out and mix with stuffing in a bowl. Stuff acorn squash with stuffing mixture and serve immediately.