Preheat oven to 350°. Place the squash and onion in a 15x10x1-in. baking pan coated with cooking spray. Combine the oil and pepper flakes; drizzle over vegetables and toss to coat., Bake, uncovered, 45-50 minutes or until tender, stirring occasionally., Meanwhile, cook linguine according to package directions; drain and place in a large bowl. Add squash mixture, Swiss chard, sage, salt and pepper; toss to combine.