Preheat your oven to 180°C (350°F) and line a baking sheet with parchment paper or a silicone mat.
In a large mixing bowl, whisk together the brown sugar and softened butter until the mixture is smooth and creamy, and you can see a slight sheen. The aroma of caramel and cinnamon will start to emerge as you mix.
Add the egg and vanilla extract to the bowl, and continue whisking until everything is well combined and the mixture is slightly fluffy. You'll notice it becomes lighter in color and more cohesive.
Gently fold in the rolled oats, raisins, cinnamon, and salt until the mixture is evenly combined. The dough will be thick and sticky, with bits of oats and raisins visible throughout.
Using a cookie scoop or tablespoon, portion out the dough onto the prepared baking sheet, spacing each cookie about 2 inches apart. Gently press down each scoop to flatten slightly, about half an inch thick.
Bake in the preheated oven for 10-12 minutes, or until the edges turn golden brown and the aroma of cinnamon and toasted oats fills your kitchen. Keep an eye on the cookies to prevent over-baking.
Remove the baking sheet from the oven and allow the cookies to rest for about 5 minutes. They will be soft but start to firm up as they cool.
Use a spatula to transfer the cookies onto a wire rack and let them cool completely for about 10 minutes. The cookies will develop a chewy interior with slightly crispy edges, and the aroma will deepen as they cool.
Once cooled, serve the cookies warm or at room temperature. They pair beautifully with a glass of milk or a cup of tea, their flavor and aroma evoking cozy childhood memories.
