Combine the dates, cocoa powder, and peanut butter in a food processor. Process until the mixture forms a thick paste, adding boiling water as needed until smooth and cohesive.
Press the mixture evenly into the prepared pan.
Place the dark chocolate and peanut butter in a heatproof bowl set over a saucepan of simmering water. Stir until melted and smooth. Add honey, if desired.
Pour the topping over the brownie base and spread evenly. Freeze until firm, about 15 minutes.