Preheat oven to 350 degrees F. Line 10 cupcake liners in a standard 12-cup muffin pan, set aside.
Whisk all dry ingredients together in a small bowl and set aside.
Place egg and sugar in a medium bowl. Beat with a hand held electric beater for 3 minutes on high, until light and looks almost like mayonnaise. Add vegetable or canola oil and vanilla extract, beat for an additional minute.
Add half the dry ingredients, beat on low until almost combined. Beat in greek yogurt and then followed by remaining dry ingredients. Beat until just combined (do not over mix). Fold in grated carrot and parsnip with a rubber spatula.
Divide batter into muffin liners (makes 10 muffins), sprinkle chopped walnuts on top. Bake for about 23-26 minutes or until a toothpick inserted in the middle comes clean.
Place pan on a wire rack to cool. Enjoy muffins for breakfast, brunch, school snack box or freeze.