In a large bowl, cream together the 1/2 cup butter, shortening, light brown sugar and white sugar until smooth. Beat in the eggs one at a time then stir in the vanilla. Combine the 1 tablespoon cinnamon, flour, baking powder and salt; stir into the creamed mixture. Cover and refrigerate dough for at least 1 hour.
Preheat the oven to 375 degrees F (190 degrees C). In a small microwave safe dish, heat the 1/2 cup brown sugar, 1/4 cup of butter and 2 teaspoons cinnamon in the microwave. Stir frequently until butter is melted and the mixture is well blended.
On a lightly floured surface, roll out each half of the dough to a 12x6 inch rectangle. Spread 1/2 of the cinnamon mixture over each rectangle. Roll each one lengthwise into a log. Cut into 1/2" segments. Bake for 8 to 10 minutes in the preheated oven.