Preheat oven to 350°F. In a microwave-safe bowl, melt the butter. Remove from microwave, stir in sugar, and melt both for 30 seconds. Stir again and melt for 60 seconds more. You want the sugar and butter to bubble up slightly, but not burn. This amount of time should do the trick.
Remove mixture from microwave and stir in bittersweet chocolate. This should melt the chocolate completely. If it doesn’t, put it in the microwave for another 15 seconds. Whisk in all other ingredients.
Pour batter into a parchment lined 8″x8″ pan. Sprinkle with chocolate chips, pretzels, peanuts, and potato chips, then drizzle everything with the caramel. Bake for 35-40 minutes, or until a knife inserted in the center of the brownies comes out clean. Allow to cool for 20 minutes before removing from pan, sprinkling with sea salt, and cutting into 9 large squares.