Preheat oven to 350°F (175°C) and line a baking sheet with parchment paper.

Cream butter and sugar until light and fluffy. Beat in egg and vanilla.

In a separate bowl, mix flour, baking soda, and salt. Gradually add to wet ingredients.

Gently fold in rhubarb and nuts or chips if using.

Drop spoonfuls onto the baking sheet, spaced about 2 inches apart.

Bake for 10–12 minutes until edges are lightly golden.

Cool on the baking sheet for a few minutes before transferring to a wire rack.