Preheat oven to 375°. In a small saucepan, bring water to a boil. Add quinoa. Reduce heat; simmer, covered, until liquid is absorbed, 12-15 minutes. Fluff with a fork; cool slightly., Meanwhile, in a large skillet, heat oil over medium heat; saute apple, onion and parsnip with celery seed and 1/2 teaspoon salt until softened, 4-5 minutes. Remove from heat; stir in sage., In a large bowl, whisk together cornmeal, flour, sugar, baking powder and remaining 3/4 teaspoon salt. In another bowl, whisk together egg and 1 cup milk. Add to cornmeal mixture, stirring just until moistened. Fold in quinoa and the apple mixture., Transfer to a greased 8-in. square baking dish. Pour remaining milk over top., Bake, uncovered, until edges are golden brown, 25-30 minutes. Let stand 5 minutes before serving. If desired, sprinkle with additional minced sage.