With a serrated knife carefully slice tops off conchas, break tops into medium-sized pieces, set aside. Line a baking sheet with parchment paper. Brush with melted butter. Microwave white chocolate chips on high until melted; stir until smooth. Pour melted chocolate onto prepared pan and sprinkle with concha pieces, push down gently to set concha piece into chocolate. Set aside for at least 2 hours until firm or refrigerate for 20 minutes. Break into pieces and serve at room temperature.