Preheat oven to 400 degrees F (200 degrees C).

Cut acorn squash in half lengthwise, seed it, and cut it into 3/4-inch slices.

Toss squash slices, Parmesan cheese, thyme, olive oil, salt, and pepper together in a bowl until the squash is evenly coated; spread into a jelly roll pan.

Roast in preheated oven until golden brown and tender, 25 to 30 minutes.