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

Peel butternut squash with a vegetable peeler. Halve lengthwise; scoop out and discard seeds.

Cut halves into 1-inch cubes.

Combine butternut squash cubes, oil, and garlic in a large bowl; toss to coat. Season with salt and pepper.

Arrange in a single layer on a baking sheet.

Roast in the preheated oven until squash is golden and tender when pierced with a fork, 25 to 35 minutes.