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

In a medium bowl, whisk together the flour, baking powder, salt, and 1 teaspoon of cinnamon. Set aside.

In a large bowl, cream the softened butter with granulated sugar and 1/2 cup of brown sugar until light and fluffy (2-3 minutes with a mixer or 4-5 minutes by hand).

Beat in the egg and vanilla extract until smooth.

Gradually add the dry ingredients in two additions, stirring gently until just combined. Do not overmix.

In a small bowl, mix 1/2 cup brown sugar and 2 teaspoons cinnamon for the filling.

Place half the dough on parchment paper, press or roll into a rectangle about 1/4 inch thick, and sprinkle half the cinnamon-sugar filling evenly over the dough.

Roll tightly from one long side to form a log, and repeat with the remaining dough.

Slice each log into 1/2-inch thick rounds and place on the prepared baking sheet about 1 inch apart.

Bake for 10-12 minutes until edges are golden and centers are set. Avoid overbaking.

Let cookies cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.