Microwave chopped dark chocolate in a small bowl until melted, about 90 seconds, stirring every 30 seconds. Repeat process in a separate bowl with peanut butter chips and tahini. Spread chocolate in an even layer on a parchment paper–lined baking sheet. Spoon peanut butter mixture over chocolate; swirl together with a knife. Sprinkle with Aleppo pepper and flaky sea salt. Freeze until firm, about 1 hour. Break into pieces.