Preheat oven to 325 degrees. Prepare the brownies according to package instructions. Crumbled three strips of bacon into the batter.
In a saucepan, melt butter. When butter is melted add brown sugar and 2 tbs heavy cream. Whisk until the sugar is dissolved.
Let the brown sugar mixture bubble for 2 minutes, stirring regularly. Remove from heat and pour into the bowl of a stand mixer. Let rest 30 minutes.
Remove the brownies from then oven when they are done and let cool.
Add the whisk attachment to the stand mixer and blend in powdered sugar, 1/2 cup at a time, until the frosting is spreadable. You may not need all of the sugar. If it's too thick, add a tablespoon of heavy cream.
Spread frosting over cooled brownies and crumble remaining bacon on top.