In a medium bowl combine the flour, baking powder, and salt. Set aside.

In a large bowl cream together the butter and sugar until smooth. Add in the egg and vanilla and mix until combined.

Add the dry ingredients to the wet ingredients and mix until combined. Stir in the cinnamon and rum. Chill the dough for 30 minutes.

Preheat the over to 375 degrees. Line 2 baking sheets with parchment paper.

Roll the dough into 1 inch balls and place on the baking sheet 3 inches apart. Using the bottom of a glass dipped in sugar flatten each ball to 1/2 inch thick.

Bake for 9-10 minutes or until cooked. Remove from oven and transfer cookies from baking sheet to cooling rack. Allow to cool completely.

To make the filling put the mascarpone cheese and powdered sugar in a large bowl. Beat with a mixer until smooth.

Place half of the cookies upside down on a cutting board or baking sheet.

Place the filling in a zip top baggie. Cut off the end and pipe a tablespoon of filling on to each cookie. Top with the remaining cookies.

Sprinkle the tops with extra cinnamon or cocoa powder if desired.