Prep: Preheat oven to 400°F. Line a 12-cup muffin tin with paper liners or grease with non-stick spray.
Whisk Dry Ingredients: In a large mixing bowl, whisk together whole wheat flour, baking powder, baking soda, salt, cinnamon, ginger and nutmeg. Whisk until well combined to ensure spices are evenly distributed.
Mix Wet Ingredients: In a separate medium-sized bowl, mix together brown sugar, oil, melted butter, eggs, vanilla extract and buttermilk.
Combine: Add the wet ingredients to the dry ingredients and stir gently. Stop mixing before flour is fully incorporated and fold in the shredded carrots. Gently fold until just combined, being careful to avoid overmixing.
Bake: Divide the batter evenly among the muffin tins. Fill the muffin tins about ¾ full. Sprinkle the tops with turbinado sugar before baking. Bake for 17-20 minutes at 400°F or until a toothpick inserted into the center comes out clean.
Cool: Let the muffins cool in the tin for 5 minutes. Then remove the muffins and place on a wire rack to cool completely.