Preheat oven to 400°. Place squash in a foil-lined 15x10x1-in. baking pan. Drizzle with oil; sprinkle with sage, salt and pepper. Toss to coat. Roast 30-35 minutes or until tender, stirring occasionally.

Meanwhile, in a large saucepan, heat oil and 1 tablespoon butter over medium heat. Add onion and garlic; cook and stir 3-4 minutes or until softened. Reduce heat to medium-low; cook 30-40 minutes or until deep golden brown, stirring occasionally. Stir in salt, pepper flakes and pepper.