📖 Instructions

1. Melt the butter: In a light-colored saucepan over medium heat, melt the butter. Continue to cook, swirling occasionally, until it foams, then browns and smells nutty. This usually takes about 5-7 minutes. Watch closely to prevent burning. Once browned, immediately pour the butter into a heatproof bowl to stop the cooking process. Let it cool slightly in the refrigerator until it is solid but still soft – about 30-45 minutes.
2. Prepare the rhubarb: While the butter is cooling, wash and dice the rhubarb into small, even pieces. You want them to be small enough to distribute well throughout the cookies. I usually aim for around 1/4-inch dice.
3. Cream butter and sugar: In a large mixing bowl, or the bowl of a stand mixer fitted with the paddle attachment, cream together the cooled brown butter and both sugars until light and fluffy. This should take about 2-3 minutes. Make sure to scrape down the sides of the bowl as needed.
4. Add egg and vanilla: Beat in the egg and vanilla extract until well combined. The mixture might look slightly curdled, but don't worry; it'll come together when you add the dry ingredients.
5. Combine dry ingredients: In a separate bowl, whisk together the flour, baking soda, salt, and cinnamon. This ensures that the baking soda and salt are evenly distributed throughout the flour, which is important for consistent baking.
6. Gradually add dry ingredients to wet: Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Be careful not to overmix, as this can lead to tough cookies.
7. Fold in rhubarb: Gently fold in the diced rhubarb until it is evenly distributed throughout the dough. The dough will be quite thick and sticky.
8. Chill the dough: Cover the bowl with plastic wrap and chill the dough in the refrigerator for at least 30 minutes. Chilling helps prevent the cookies from spreading too much during baking and also allows the flavors to meld together.
9. Preheat oven: Preheat the oven to 375°F (190°C). Line baking sheets with parchment paper. Parchment paper prevents the cookies from sticking and makes cleanup a breeze.
10. Scoop and bake: Scoop rounded tablespoons of dough onto the prepared baking sheets, leaving about 2 inches between each cookie. For evenly sized cookies, you can use a cookie scoop.
11. Bake: Bake for 10-12 minutes, or until the edges are golden brown and the centers are set. The cookies should still be slightly soft to the touch.
12. Cool: Let the cookies cool on the baking sheets for a few minutes before transferring them to a wire rack to cool completely. This prevents them from breaking while they are still warm and soft.