Prepare Dry Ingredients: In a mixing bowl, combine the instant oats, whole wheat or gluten-free flour, baking powder, cinnamon, and salt. Whisk them together thoroughly to ensure the ingredients are evenly distributed.
Mix Wet Ingredients: In a separate bowl, whisk together the melted coconut oil or butter with the egg and vanilla extract. Once smooth, add in the maple syrup and milk, mixing until fully blended.
Combine Wet and Dry Mixtures: Pour the wet ingredients into the dry ingredients. Stir gently just until the flour mixture is incorporated. Avoid overmixing to keep the cookies tender.
Add Raisins: Fold in the raisins carefully, distributing them evenly throughout the dough without breaking them up.
Chill the Dough: Cover the dough and place it in the refrigerator for 30 minutes. This step firms up the dough, making it easier to shape and enhancing the cookie texture.
Preheat Oven and Prepare Baking Surface: Set your oven to 325°F (163°C). Line a baking sheet with a silicone baking mat or parchment paper to prevent sticking and promote even baking.
Shape the Cookies: Use a cookie scoop or spoon to drop 15 rounded portions of dough onto the prepared sheet. Gently press each mound down to your preferred thickness using a spatula.
Bake to Perfection: Bake the cookies for 10 to 13 minutes, or until the edges turn lightly golden and the centers are set. Avoid overbaking to maintain their chewy texture.
Cool Before Serving: Allow the cookies to cool on the baking sheet for 10 minutes, then transfer them to a wire rack to cool completely.