Make the compote: In a small saucepan, combine rhubarb, 1/4 cup sugar, and water. Cook over medium heat for 8-10 mins, stirring, until jam-like. Remove from heat; stir in lemon juice and 1/2 tsp vanilla. Cool completely in fridge.

Preheat oven to 350°F (175°C). Line baking sheets with parchment paper.

Whisk together flour, baking powder, and salt in a medium bowl.

In a large bowl, cream softened butter and 1/2 cup sugar until light and fluffy. Beat in egg and 2 tsp vanilla until combined.

Gradually mix the flour mixture into the wet ingredients until a soft dough forms. Chill for 20-30 mins for easier handling.

Portion dough into 1-inch balls. Place on baking sheets 2 inches apart. Make a deep indentation in the center of each with your thumb or a spoon.

Fill each indentation with about 1 tsp of the cooled rhubarb compote.

Bake for 12-15 minutes, until edges are set and lightly golden. Cool on pan for 5 mins, then transfer to a wire rack to cool completely.