Preheat the oven to 350°F(177°C). Grease 8 1/2 * 4 1/2 inch (21,5*10,5cm) loaf pan and line the bottom and sides with parchment paper, about 2 inches(5 cm) of overhang on each side. If you like, you can grease and flour the dish instead of parchment paper.
Place the flour, cinnamon, nutmeg, baking powder (and salt if using) into a medium bowl and mix. Set aside.
Roughly chop the walnuts into small pieces with a sharp knife, set aside.
Peel and grate the carrots, set aside.
Put the sugar and eggs in a large bowl and mix with a whisk until just combined for almost 45 seconds.
Mix in the olive oil and vanilla extract, stir with a whisk until just combined.
Add the flour mixture in 2 batches and stir until just combined. You can use a whisk in the first batch but it will be easier to use a spoon/spatula in the end to mix easily.
Add the carrots and stir with a spoon/spatula. Mix in the walnuts.
Pour the batter into the loaf pan with the help of a spoon.
Bake for 50-55 minutes or until a toothpick comes out clean that is inserted in the center and the top is golden brown. After you remove the pan from the oven, leave in the pan until it cools completely, at least for 1 hour.