Start by browning the butter. Add the butter to a small saucepan and place over medium-low heat. Stir as the butter begins to melt. As the butter melts it will start to foam and sputter. Stir until the butter completely melts and the sputtering starts. You should see small dairy solids at the bottom, and those should start to turn golden brown. The butter will smell nutty and toasty. Take off the heat and pour into a bowl to cool completely.
1 cup unsalted butter
While the brown butter cools you can toast the walnuts! This step is optional but I think it adds a flavor dimension to the cookies. Preheat the oven to 350℉/175℃ and place the chopped walnuts in a small baking dish. Toast for 5-7 minutes. Take out of the oven and let cool.
½ cup walnuts
In a medium bowl, whisk together the flour, salt, baking soda and spices. Set aside.
1 ¾ cup all purpose flour, 1 teaspoon ground cinnamon, ¼ teaspoon ground nutmeg, ¼ teaspoon ground cardamom, 1 teaspoon baking soda, 1 teaspoon kosher salt
Add the light brown sugar, white sugar and vanilla extract to the cooled brown butter. Whisk until smooth.
1 cup light brown sugar, ¼ cup white sugar, 2 teaspoons vanilla extract
Add the 2 eggs into the melted butter, and whisk until just combined.
2 large eggs
Pour the flour mixture into the sugar mixture and stir until just combined. Stir in the rolled oats.
2 ½ cups rolled oats
Stir in the chocolate chips and toasted walnuts. Cover the bowl with plastic wrap and place in the fridge for at least 45 minutes, or up to overnight.
1 cup semisweet chocolate chips
After 45 minutes, preheat the oven to 350℉/175℃ and line two baking trays with parchment paper.
Using a medium cookie scoop or a tablespoon, scoop out 1.5-2 tablespoons of dough. Place on the prepared baking sheets, keeping the cookie dough balls about 3-4 inches apart.
Bake 1 sheet at a time for 11-13 minutes. The edges will have set and turned golden brown but the middles might look underbaked which is fine. Let cool for 10 minutes on the baking sheet before tranferring to a wire cooling rack to cool completely.
I recommend keeping the cookie dough balls that aren't being baked right away in the fridge! That way they don't get too warm. If they get too warm they will spread out while baking.
Video
Notes
My recipes have been developed and tested in metric grams. I highly recommend using a weighing scale and measuring out your ingredients the metric way.
Walnuts: feel free to swap out the walnuts for pecans.
Chocolate Chips: I'm using semisweet chocolate chips but you can use milk chocolate chips or dark chocolate chips if you prefer. You can also use butterscotch chips or peanut butter chips.
Overnight Chilling: if you're chilling the cookies for more than a few hours you may need to let the cookies come to room temperature for 15-20 minutes before scooping out the cookie dough.
Oats: make sure you're using rolled oats or old-fashioned oats. Instant oats or porridge oats will make the cookies too dry!
Butter: I use European-style butter, like Kerry Gold, in my recipes. This will make your cookies much creamier and richer.Cardamom: If you can't find ground cardamom you can swap it out for ground ginger.Salt: If you don’t have kosher salt, halve the amount of salt called for in the recipe. 1 teaspoon kosher salt = ½ teaspoon fine salt. Please note I am using Diamond Crystal Kosher Salt and not Morton Salt, which is a coarse kosher salt. Coarse kosher salt is much too salty for this recipe. Storage: keep the baked cookies in a tupperware for up to 1 week at room temperature. Freeze unbaked cookie dough balls for up to 2 months. When ready to bake, take them out of the freezer and bake at the same temperature as above but for an extra minute or two.