01 - Preheat the oven to 350°F (175°C) and line two baking sheets with parchment paper.
02 - In a medium bowl, whisk together the flour, baking powder, baking soda, salt, cinnamon, ginger, and nutmeg until evenly mixed.
03 - In a large bowl, cream the softened butter with the brown sugar and granulated sugar using a hand mixer or stand mixer until the mixture is light and fluffy.
04 - Beat in the egg and vanilla extract until fully combined and smooth.
05 - Stir in the grated carrots, parsnip, and apple until evenly distributed throughout the batter.
06 - Gradually fold the dry ingredient mixture into the wet ingredients, mixing gently until just combined to avoid overmixing.
07 - Fold in the rolled oats along with chopped walnuts and raisins if using, ensuring an even distribution.
08 - Drop tablespoon-sized mounds of dough onto the prepared baking sheets, spacing them approximately 2 inches apart.
09 - Bake for 13 to 15 minutes or until the cookie edges turn lightly golden.
10 - Allow cookies to cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.