01 -
Preheat oven to 375°F/190°C, and line a cookie sheet with parchment paper or a silicone mat.
02 -
In a large mixing bowl, using a stand or hand mixer, beat the butter, sugar, and egg until smooth and creamy.
03 -
Add flour, ground cinnamon, baking soda, baking powder, and salt, and slowly beat again until just combined.
04 -
Fold in the diced rhubarb, then using a small 1-inch cookie scoop, scoop out balls of dough and place them onto the prepared cookie sheet.
05 -
Bake in the preheated oven for 12-14 minutes, or until set and lightly brown at the bottom.
06 -
Allow to cool for 5 minutes on the cookie sheet, then transfer to a wire rack to cool completely.