. Over medium low heat, add butter to a skillet (preferably a lightly colored skillet so that you can see when the butter is browned). Allow butter to melt. Simmer until foamy and brown bits begin to collect on the bottom of the pan. Pour butter in a container, with the brown bits, and refrigerate for about 1-2 hours, until butter has solidified.
Preheat oven to 350 degrees F.
Spoon butter into the bowl of a stand mixer with the paddle attachment. Beat butter, powdered sugar, sugar, and brown sugar together on medium speed for about 3-5 minutes, until mixture is fluffy and lighter in color. While continuing to mix, add oil and increase speed to medium and add the egg, sour cream, and vanilla extract. Scrape down the sides of the bowl and continue to mix for another minute.
Add flour, baking soda, baking powder, kosher salt, and a pinch nutmeg to a separate bowl and whisk together. Add dry ingredients to the butter mixture and mix until just combined, about 15 seconds.
Put ¼ cup of sugar into a mixing bowl. Using a cookie scoop or a tablespoon, spoon about 1 ½ tbsps and roll into a ball. Roll the cookie around in sugar and place onto a cookie sheet lined with parchment paper or sprayed with nonstick baking spray.
Bake about 5-6 cookies at a time for 12-14 minutes.