Cook bacon in a large skillet over medium heat until fully rendered and lightly browned, about 5 minutes. Meanwhile, mash the garlic with several pinches of salt with the side of a knife until pasty. Turn heat to medium low and add the garlic to the bacon and cook until lightly browned. Add a little vegetable oil if there is not enough fat to generously coat the pan. Add the cassava flour and cook, constantly stirring and shaking the pan. (The flour toasts quickly, so fold it in at the bottom of the pan.) Turn off heat, and stir in the butter and more salt to taste. Serve as a side with the feijoada to soak up the juices.
