Preheat the oven to 350°F. Spray a 9 x 5-inch metal non-stick loaf pan with baking spray. Set aside.
In a medium size mixing bowl, sift together the flour, sugar, baking powder, salt and baking soda.
In a separate bowl, whisk together the buttermilk, melted butter, eggs and vanilla.
Add the wet to the dry ingredients mixing until fully combined.
To make the cinnamon swirl, mix together the melted butter, brown sugar and ground cinnamon.
Pour ½ of the batter into the loaf pan. Dollops ½ of the cinnamon swirl mixture over the batter then use a knife to swirl it through the batter. Top with the remaining batter and cinnamon and repeat swirling the cinnamon through the batter.
Bake for 40 minutes then check the center with a toothpick for doneness. Cover with a piece of aluminum foil and continue to bake for an additional 10-15 minutes or until a toothpick inserted into the middle comes back clean.
Cool on a cooling rack in the pan for 1 hour then remove from the pan to cool completely.
To make the glaze, mix together the powered sugar with 3 Tbsp of heavy cream. Add additional cream 1 Tbsp at a time until it reaches spreading consistency. Pour over the cooled cinnamon roll bread.
If you're unable to find whole buttermilk use a low fat but not fat free buttermilk for the best results.