Heat oven to 350°F. Line 12 baking cups with paper liners, or mist with cooking spray. Set aside.
Combine flour, oats, baking powder, baking soda, cinnamon, nutmeg, ginger, and salt together in a large mixing bowl. Whisk until combined. Set aside.
In a separate bowl, combine the eggs, Greek yogurt, honey, oil, vanilla, carrots and raisins (if using). Stir until combined.
Add the wet ingredients to the dry ingredients, and stir until just combined. (Try not to overmix.)
Portion the batter evenly between 12 baking cups.Bake for 18-20 minutes, or until a toothpick inserted in the center of the muffin comes out clean. Transfer pan to a cooling rack, then drizzle with icing once the muffins reach room temperature. Serve immediately. Or let cool to room temperature, then store in a sealed container for up to 2 days, or freeze.