01 -
Turn your oven to 375°F (190°C) and set up a baking sheet with either silicone or parchment paper on top.
02 -
In a big bowl, grab a hand or stand mixer and blend the butter, brown sugar, and egg until everything's smooth and creamy.
03 -
Dump in the flour, cinnamon, baking powder, baking soda, and salt, and gently mix until the dough just comes together.
04 -
Gently stir the rhubarb into the cookie dough. Using a small cookie scoop (1-inch), portion out balls onto the baking sheet.
05 -
Pop into the oven and let bake for around 12 to 14 minutes, or until they’re just set with a slightly golden underside.
06 -
Let them cool right on the baking sheet for around 5 minutes, then move them to a wire rack to cool down all the way.