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

In a medium bowl, whisk together flour, baking powder, baking soda, and salt.

In a large bowl, cream butter and brown sugar until light and fluffy. Add egg and vanilla extract, mixing well.

Gradually mix in dry ingredients until dough forms.

Scoop dough into 1-inch balls, place on baking sheet, flatten slightly.

Bake 10–12 minutes until edges are lightly golden. Cool completely on wire racks.

Beat softened butter with powdered sugar and vanilla. Add cream until smooth.

Spread filling on one cookie, add strawberry jam, top with second cookie to sandwich.