Arrange bacon side by side on a plate lined with parchment paper. Cover with another sheet of parchment paper or microwave-safe cover and cook on high for 4-6 minutes. Rotate the plate half way through cooking so bacon cooks evenly. Place bacon on a paper towel lined plate to drain, then crumble or slice into small pieces and add to popcorn.
Add butter to a microwave safe bowl and heat on high for 30 seconds. Rotate and heat for another 15-30 seconds, watching to be sure it doesn’t boil over.
Pour butter over popcorn then sprinkle with truffle salt. Mix to combine. Then add parmesan cheese and toss to coat. Serve warm or at room temperature.