After much experimenting, I think I've found the right brownie mix.
Dark chocolate carries the primary weight in this bake, dictating both the structural set and the bitter balance against two cups of sugar. Selecting a bar containing at least 60 percent cocoa solids prevents the batter from turning cloying once the confectionery bars are folded in. Technique matters significantly when integrating the elements.
Allowing the pan to rest undisturbed for a minimum of two hours at room temperature solidifies the fats and sets the crumb structure. Storing leftovers in an airtight container for up to three days actually concentrates the fruit and chocolate flavors as the sugars redistribute evenly throughout the matrix.