Prepare a 9 x 13 inch baking pan with parchment paper. Set aside.
First, brown your butter by placing in a large saucepan or pot on medium low heat. Stir until butter is melted. Continue to stir and heat until butter has past the foamy stage, is fragrant and brownish in color (about 5 minutes).
Stir in vanilla extract, salt, and cinnamon to browned butter.
Then, immediately add marshmallows to browned butter to prevent any further cooking of the butter. Continue to stir using a wooden spoon on low to medium low heat until marshmallows are completely melted.
Remove pot from the heat and set on heat proof surface. Stir in cereal until incorporated and then fold in the butterscotch chips.
Transfer rice krispie treat base into prepare pan by scooping out large spoonfuls and patting the mixture into a level rectangle with your hands.
Next make your peanut butter chocolate ganache.
Melt german chocolate by chopping a baking bar into chunks, or using baking chips in a heat proof bowl in the microwave or by using a double broiler. If you choose to use the microwave method, heat in 30 second increments stirring between.
Add peanut butter to melted chocoalte and stir until smooth and creamy.
Pour peanut butter ganache onto rice krispie treats and level with an offset spatula or small rubber spatula.
Let Scotcheroos sit at room temperature for an hour for the ganache to set or place in fridge for about 20 minutes.
Slice using a sharp knife. Sprinkle with flaky sea salt if desired.