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

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

In a large bowl, cream softened butter with granulated and brown sugars until fluffy, about 2 minutes.

Beat in the egg and vanilla until smooth, scraping down the bowl as needed.

Gradually add dry mixture to wet until just combined. If dough is too sticky, add 1 tbsp flour at a time.

For the filling, stir brown sugar and cinnamon in a small bowl.

Roll half the dough on parchment into a ¼-inch thick rectangle.

Sprinkle evenly with cinnamon-sugar, then roll tightly into a log. Repeat with remaining dough.

Slice logs into ½-inch rounds and place on the baking sheet, spacing apart.

Bake 10–12 minutes until golden at the edges. Cool 2 minutes on the sheet, then transfer to a wire rack.