Cream butter, cream cheese, and sugar in a large mixing bowl until light and fluffy. Add in egg and vanilla; beat until combined. Sift in flour and baking powder. Mix just until combined, being careful not to overmix. Dump dough onto counter and knead 2 or 3 times just to incorporate any leftover flour. Divide into 2 discs and wrap in plastic wrap. Refrigerate for about an hour.

To make cinnamon mixture, combine sugar and cinnamon. Melt butter; set aside.

Working with one disc of dough at a time, roll out into a 12 x 8 inch rectangle on a floured surface. Brush dough with half of the melted butter. Sprinkle with half of the cinnamon mixture. Starting from one of the short sides, roll into a tight log. Wrap in plastic wrap. Repeat with other disc. Refrigerate for at least 4 hours.

When ready to bake, preheat oven to 375F.

Use a sharp knife to cut dough into ¼-inch rounds; place on ungreased baking sheet. Bake for 8 to 10 minutes or until edges are just slightly golden. Cool on wire rack.