Preheat the oven to 350°F (175°C) and line a muffin tin with cupcake liners.

In a large bowl, whisk together the flour, granulated sugar, brown sugar, baking powder, baking soda, salt, cinnamon, and nutmeg.

In another bowl, mix the oil and eggs until well combined. Stir in the grated carrots, walnuts, and raisins if using.

Combine the wet ingredients with the dry ingredients and mix until just combined.

Divide the batter evenly among the cupcake liners, filling each about 2/3 full.

Bake for 20-25 minutes or until a toothpick inserted into the center comes out clean. Let cool completely.

In a mixing bowl, beat the softened cream cheese and butter together until smooth.

Gradually add the powdered sugar and vanilla extract, mixing until creamy and smooth.

Once the cupcakes are completely cool, frost them with the cream cheese frosting.