Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper for easy cleanup and to prevent sticking.

In a large mixing bowl, combine rolled oats, flour, baking soda, cinnamon, and salt, whisking together until evenly distributed.

In a separate bowl, whisk together melted coconut oil or butter, honey or maple syrup, brown sugar if using, egg, and vanilla extract until smooth and well combined.

Pour the wet ingredients into the dry ingredients and stir until just combined. The mixture should be thick but scoopable.

Fold in the raisins, distributing them evenly throughout the dough. If the dough seems too dry, add milk one tablespoon at a time until it reaches a thick cookie dough consistency.

Drop rounded tablespoons of dough onto the prepared baking sheet, spacing them about 2 inches apart. Flatten each cookie slightly with the back of your spoon or your palm.

Bake for 12-15 minutes, until the edges are lightly golden but the centers still look slightly soft. Don't overbake.

Allow cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely. They'll firm up as they cool while maintaining a chewy center.