Preheat oven to 450°.
Combine first 5 ingredients in a bowl. Combine 2 tablespoons sugar mixture and squash; toss gently. Arrange squash in an 11 x 7-inch baking dish coated with cooking spray. Arrange salmon on top of squash; brush with mustard. Sprinkle fish with remaining sugar mixture. Bake at 450° for 15 minutes or until fish flakes easily when tested with a fork. Garnish with parsley sprigs, if desired.