Preheat oven to 375 degrees F (190 degrees C). Line a baking sheet with aluminum foil.
Stir olive oil and garlic salt together in a small bowl; pour into a large resealable plastic bag. Add carrots to the plastic bag, seal, and shake to coat carrots completely in oil mixture. Arrange coated carrots onto the prepared baking sheet.
Roast carrots in preheated oven until crisp-tender, about 45 minutes. Sprinkle 1/4 cup Parmesan cheese over carrots and continue roasting until cheese is lightly browned, 5 to 10 minutes. Garnish with additional Parmesan cheese to serve, according to your taste.