Preheat the oven to 425°F. Line a baking sheet with parchment paper or spray with nonstick cooking spray. Set aside.
Slice the top and bottom off of the butternut squash. Using a vegetable peeler, peel off the outside skin. Slice the squash in half, then use a spoon to scoop out the inner seeds and stringy bits. Next, slice the squash into 1″ strips. After that, slice each one into 1″ cubes that are all similar in size (so they cook evenly).
In a small bowl, mix together 1 tsp dried thyme, 1 tsp garlic powder, 1 tsp salt and 1 tsp ground black pepper.
Add the chopped butternut squash to a large bowl and drizzle 3 Tbsp olive oil on top. Sprinkle the spice mix over the squash, then toss together until each cube is evenly coated.
Add the squash cubes to the baking sheet in a single layer. Try to spread them out so that they will cook on all sides evenly. Place in the oven to bake for 20-25 minutes, or until edges are firm and squash is tender when poked with a fork.