Start by preheating your oven to 375°F and lining your baking sheets with parchment paper. While the oven heats, measure out all your dry ingredients (flour, baking soda, salt, oats) into a bowl and whisk them together until evenly combined—this ensures the leavening agents are distributed uniformly throughout the dough. Chop your walnuts into roughly 1/4-inch pieces and have all your mix-ins (raisins, chocolate chips, coconut) ready and accessible. This upfront organization means you won't scramble mid-recipe and ensures smooth, uninterrupted baking.

In a large mixing bowl, combine the softened butter, light brown sugar, and granulated sugar. Beat on medium speed for 2-3 minutes until the mixture is light, fluffy, and pale in color. This creaming process incorporates air into the dough, which helps the cookies rise slightly and develop a better texture. The volume should visibly increase as you beat.

Add the peanut butter to the creamed mixture and beat until fully combined, about 1 minute. Then add the eggs one at a time, beating well after each addition to ensure they're properly incorporated—this prevents lumpy batter and helps emulsify the mixture. Finally, add the vanilla extract and beat until everything is smooth and uniform. The batter should look cohesive and creamy at this point.

Add the dry ingredient mixture from Step 1 to the creamed mixture, beating on low speed just until the flour is incorporated and no streaks remain. Be careful not to overmix at this stage—overmixing develops gluten, which can make cookies tough. I find that stopping as soon as the flour disappears gives you the most tender cookie texture.

Using a wooden spoon or sturdy spatula, fold the chopped walnuts, raisins, chocolate chips, and coconut into the dough from Step 4. Stir gently until everything is evenly distributed throughout—you want each cookie to have a good mix of all the mix-ins. Drop rounded tablespoon-sized portions of dough onto your prepared baking sheets, spacing them about 2 inches apart. Gently flatten each cookie with the palm of your hand or bottom of a measuring cup to about 1/4-inch thickness. This helps them bake more evenly.

Bake the cookies at 375°F for 8-12 minutes, watching closely toward the end. They're done when the edges are set and lightly golden but the centers still look slightly underbaked—they'll continue to cook a bit as they cool on the pan. Let the cookies cool on the baking sheet for 2-3 minutes so they firm up enough to move without breaking, then transfer them to a wire rack to cool completely. I find that slightly underbaked cookies stay chewier once they've cooled completely.