Combine the flour, sugar, baking soda, baking powder, and salt in a large mixing bowl.
Whisk the eggs and oil together.
Slowly add wet ingredients to the dry ingredients. Let them mix for a minute or two until there are no dry ingredients showing. Stop the mixer, scrape down the bowl and add the cinnamon and walnuts. Mix until just combined, Stop the mixer and scrape down. Add the grated carrot until it's mixed evenly. The batter will thin out and this is normal so don't panic haha.
Scoop the batter into the cupcake tin lined with cupcake liners. Fill 1/2 way. It's important to not over fill these as they have a lot of raising agents in them (bicarb sode and baking powder) and will explode in your oven!
Bake them for 20-30 min or until a skewer comes out clean. Set them aside on a cooling rack to cool completely before frosting
Line a piping bag with a Wilton 6B French Star Tip and fill with cream cheese frosting. Pipe in a swirl starting in the center of the cupcake. To finish off sprinkle some cinnamon on top and some walnuts.