Preheat the oven to 350° F and line baking pans with parchment paper or spray with cooking spray. Set aside. In a large bowl. use an electric mixer to cream together the butter and sugar, on medium speed for 1-2 minutes. With the mixer on low, add in the egg, vanilla, heavy cream, baking powder and salt. Combine by mixing for one minute on medium speed. Turn the mixer down to low again, and add in the flour slowly. Mix until just combined.
Fold in the cinnamon sugar filling. Do not over mix! You want the filling to be swirled in rather than well-combined.
Roll 2" balls of cookie dough and place dough a couple of inches apart on the baking pans. Bake for 12-15 minutes until the edges look slightly golden brown.
While the cookie bars are baking, combine the powdered sugar, butter and 1 tablespoon of cream in a small bowl. Add more cream if the icing is too thick.
Once the cookies come out of the oven, drizzle the icing on top. Let the cookies cool for a few minutes. Enjoy!