Preheat oven to 350° F. In a large bowl, cream together butter and brown sugar. Beat in eggs and vanilla. In a separate bowl, whisk together the flour, oatmeal, salt, cinnamon and baking soda. Stir the dry ingredients into the wet. Gently stir in the rhubarb.
Drop dough by tablespoons onto a cookie sheet. Bake in a preheated oven for 15-18 minutes or until lightly browned. Remove from the oven and sprinkle with coarse sugar if desired. Let cool on the tray for 2 minutes before moving to a wire rack to cool completely.
Frosting Directions
To make the cream cheese frosting, beat the cream cheese and the butter until combined and fluffy. Add the powdered sugar and vanilla and beat until smooth. Add milk as needed to get a spreadable consistency.
Notes
You can make this recipe using fresh or frozen rhubarb. If you choose to use frozen rhubarb thaw the rhubarb first and let any excess liquid drain off. Don’t squeeze any liquid out, just drain what naturally thaws out of the rhubarb.
If the cookies are spreading too much, the dough is probably too warm. Chill the dough for 30 minutes or longer and then try baking. Variations in the temperature of the butter, protein content of the flour, and water content of the rhubarb can all have an impact on how much the cookies spread.
Thanks to the rhubarb, these cookies will be softer the second day. Store tightly covered or freeze for longer storage.