In a large bowl, toss butternut squash with garlic, olive oil, rosemary, salt and pepper.
Arrange coated squash into a 9x13 casserole dish and evenly top it with chopped bacon.
Bake for 30-35 minutes, until squash is tender and lightly browned.
Sprinkle Parmesan and cheddar cheese evenly over the top of the butternut squash and bacon. Bake for an additional 10 minutes, until the cheese is completely melted, the butternut squash is tender, and bacon is crisped and cooked through.