Measure out all ingredients and set them in small bowls within arm's reach—this is especially important for baking since timing matters. Preheat your oven to 350°F so it's ready when you need it. Let the butter soften to room temperature (it should yield easily to finger pressure but still hold its shape); this ensures it creams properly and creates the light, fluffy base your cookies need. Chop the walnuts into roughly ¼-inch pieces and have your raisins ready.

In a large bowl, combine the softened butter, brown sugar, and granulated sugar. Using an electric mixer on medium speed, beat for 2 minutes until the mixture is light, fluffy, and noticeably paler in color. This creaming process incorporates air into the butter, which helps your cookies rise and become tender. I find this step is crucial—don't rush it or skip the full 2 minutes.

Add the eggs one at a time to the creamed butter mixture, beating for about 30 seconds after each addition to fully incorporate. Then add the vanilla extract and molasses, mixing on medium speed for another minute until the mixture is smooth and well combined. The molasses adds a subtle depth and chewiness that really makes these cookies special—don't skip it even though the amount seems small.

While the wet ingredients are mixing, whisk together the flour, baking soda, ground cinnamon, and salt in a separate bowl. Whisking combines the leavening agent evenly throughout the flour, which prevents dense spots in your baked cookies. Make sure the cinnamon is freshly ground if possible—pre-ground cinnamon loses potency over time, and fresh makes a noticeable difference in flavor.

Pour the dry ingredient mixture from Step 4 into the wet mixture from Step 3. Fold gently with a spatula or stir on low mixer speed just until the flour disappears—overworking the dough at this stage develops gluten, which makes cookies tough and dense. Stop as soon as you don't see any white streaks of flour.

Using a spatula or wooden spoon, fold in the rolled oats, raisins, and chopped walnuts until evenly distributed throughout the dough. The dough will be thick and somewhat stiff, which is perfect. Chill the dough in the refrigerator for 30 to 60 minutes—this prevents the cookies from spreading too much during baking and helps them hold their shape. The rest also allows the flavors to meld together.

Remove the chilled dough from the refrigerator and scoop it into rough balls about 1½ inches in diameter, placing them about 2 inches apart on ungreased or parchment-lined baking sheets. Bake for 12 to 14 minutes until the edges are light golden brown but the centers still look slightly underdone—they will continue cooking on the hot pan after removal. Let the cookies cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely. This cooling on the sheet firms them up just enough so they don't break when you move them.