Preheat oven to 400 degrees F. Place oats, cooled cooked quinoa, and walnuts in a greased 15x10x1-inch baking pan; toss together. Add oil; toss to coat. Spread in an even layer. Bake for 10 to 12 minutes or until toasted, stirring once. Remove; cool in pan on a wire rack.
Grease twelve 2 1/2-inch muffin cups; set aside. In a large bowl stir together all but 1/4 cup of the quinoa mixture,the all-purpose flour, whole wheat flour, sugar, baking powder, baking soda, and salt. Make a well in the center of flour mixture; set aside.
Finely shred 2 teaspoons peel from the orange. Juice the orange to get 3 tablespoons. In a 2-cup measure whisk together buttermilk, eggs, sour cream, butter, orange juice, and orange peel. Add all at once to flour mixture. Gently stir just until moistened (batter should be lumpy).
Spoon batter into prepared muffin cups, filling each three-fourths full. Sprinkle with remaining quinoa mixture. Bake for 15 minutes or until golden. Cool in cups on a wire rack for 5 minutes. Serve warm. If desired, serve with orange marmalade.