First things first. Preheat your oven to 350°F (175°C). This is a crucial step. A well-heated oven ensures that the cookies bake evenly and achieve that perfect chewiness.

Grab your baking sheet and line it with parchment paper. This makes for easy cleanup and prevents the cookies from sticking, keeping them intact and perfectly shaped.

In a large mixing bowl, whisk together the melted butter, brown sugar, and granulated sugar until you get a smooth, glossy mixture. It should look luscious and inviting. Add the vanilla extract, egg, and the egg yolk. Whisk until well combined. The eggs will help bind everything together, creating that cake-like texture we adore.

In a separate bowl, mix the flour, baking soda, salt, ground cinnamon, and freshly grated nutmeg. Stir this together until evenly incorporated. This step allows the spices to meld, enhancing the cookie’s flavor profile.

Gradually add the dry mixture to the wet ingredients. Use a spatula or a wooden spoon to combine the two until you see no more flour. Don’t overmix; we want tenderness. It should be slightly sticky and gooey from the melted butter.

Now for the star players! Fold in the old-fashioned rolled oats, raisins, and if you’re feeling adventurous, the chopped nuts. Combine them gently, ensuring everything is evenly distributed. The oats add that hearty texture, while the raisins offer delightful bursts of sweetness.

Using a cookie scoop or a tablespoon, drop rounded mounds of batter onto the prepared baking sheet, leaving about two inches between them. They’ll spread while baking, so give them space.

Pop the sheet into the preheated oven. Bake for 10-12 minutes or until the edges are golden brown. They’ll look soft in the center but will firm up as they cool. Trust me; the smell will be hard to resist!

Once baked, remove the cookies from the oven. Allow them to cool on the baking sheet for about 5 minutes. Then transfer them to a wire rack to cool completely. This step is not just to let them cool; it also allows them to settle and develop that irresistible texture.