In a medium saucepan, melt the butter over medium heat. Bring it to a slow rolling boil. Stir until butter starts to become a light amber or deep gold color. Watch carefully as it can burn. Remove from heat.
Let butter cool for 15 - 20 minutes.
Preheat the oven to 350°F.
Stir in the brown sugar, sugar, eggs, and vanilla into the cooled butter mixture. Stir to combine. Add flour, baking soda, and salt. Fold all ingredients together.
Stir in butterscotch chips, chocolate chips, and pretzels.
Drop the dough on the baking sheet. Bake for 9 - 13 minutes, or until the edges become lightly golden.
If desired sprinkle with a pinch of flaked sea salt on top of the cookies.