Place the milk, sugar, and butter cubes into a medium microwave safe bowl. Microwave mixture until warm but not hot. Butter should be at least mostly melted.
Add the yeast to the warm milk and allow to sit for 10 minutes, until foamy.
When your yeast mixture has proofed (is foamy) pour into the bowl of your stand mixer.
Add 1 cup of the flour, along with the salt and egg.
Using paddle attachment (or a large spoon if you're not using a mixer) start to blend ingredients together while adding remaining flour in 1/2 cup intervals.
When the dough starts to leave the sides of the bowl, switch to your paddle attachment and allow dough to knead for 5 minutes. Or, pour dough out onto a well floured surface and knead by hand for 5-7 minutes.
Pat dough into a ball, and place in a large, lightly oiled bowl to rise for 1 hour, or until doubled in size.
While dough is rising, mix together the brown sugar, cinnamon, and crumbled bacon in a small bowl.
When dough is doubled in size, remove from bowl onto a floured surface and roll out from the center into a large rectangle (about 12x14).
Spread the dough evenly with 1/2 cup of peanut butter and sprinkle with the brown sugar/cinnamon/bacon mixture.
Starting at the long side of the rectangle, roll dough up tightly, and pinch the seam to seal the dough.
Slice the dough into 12 equal rolls.
Preheat oven to 350 degrees.
Spray a 9x13 inch pan with non-stick spray, and place rolls in the pan.
Allow the rolls to rise for 20 minutes.
Bake rolls 15-20 minutes until lightly golden brown.
When rolls come out of the oven combine all of the frosting ingredients with a hand mixer or whisk until well combined.
Spread frosting over warm rolls as desired.