Preheat oven to 375°F. Line two baking sheets with parchment paper. Toss diced rhubarb with 1 tablespoon flour and set aside.
In a large bowl, cream together softened butter, brown sugar, and white sugar until light and fluffy, about 2-3 minutes.
Beat in egg and vanilla extract until fully incorporated, scraping down bowl as needed.
In separate bowl, whisk together 1 3/4 cups flour, cinnamon, baking soda, baking powder, and salt.
Gradually add dry ingredients to wet ingredients, mixing just until combined. Don't overmix.
Gently fold in flour-coated rhubarb until evenly distributed throughout dough.
Drop rounded tablespoons of dough onto prepared baking sheets, spacing 2 inches apart.
Bake for 12-14 minutes until edges are golden and centers look set.
Cool on baking sheet for 2 minutes, then transfer to wire rack to cool completely.