Preheat the oven to 350℉
Begin by preparing the brown butter. In a medium saucepan or skillet, melt the butter over medium heat.
Once melted, whisk the butter constantly for 3-4 minutes, watching closely to avoid burning. The butter will start to bubble, foam, and turn golden brown with a nutty fragrance.
When the butter has small brown bits and has reached a golden brown color, remove it from heat. Continue to cook for another minute, but make sure it doesn’t get too dark.
Transfer the brown butter to a large, heat-safe mixing bowl and allow it to cool completely.
Once cooled, add the brown sugar and granulated sugar to the bowl. Whisk until smooth.
Add the eggs and vanilla extract to the sugar mixture and whisk until everything is well combined.
In a separate bowl, combine the flour, oats, baking soda, salt, cinnamon, cardamom, nutmeg, ginger, cloves, and allspice. Whisk together to ensure everything is evenly distributed.
Gradually add the dry ingredients to the wet ingredients, mixing with a rubber spatula until just combined.
Let the dough rest for 5-10 minutes to firm up slightly before scooping.
Using a cookie scoop (about 1.5 tablespoons in size), scoop the dough and roll it into balls. Place them on a baking sheet lined with parchment paper or a silicone mat.
Bake for 8-10 minutes, or until the edges of the cookies are golden brown.
Allow the cookies to cool completely on a cooling rack.