Preheat oven to 350 degrees
You can use cupcake liners in a muffin pan, or just a muffin. Pan. I used a brioche pan, filled 1/4 of the way up, because I wanted that design.
Whisk together the flour, salt, baking powder. Set aside.
In a medium-sized saucepan, melt butter and brown sugar over med-low heat, whisking to combine.
Lower heat to very low and add cream cheese, whisking until smooth. Remove from heat, add vinegar and vanilla. Allow to cool to room temperature.
Thoroughly whisk in the egg. Whisk in the dry ingredients.
Divide the mixture evenly among the 12 muffin cups in the prepared pan.
Bake at 350 degrees F for 16 minutes.
Cool completely and sprinkle with powdered sugar before serving.