Chocolate Taiyaki

Prepare the chocolate ganache filling: In a small saucepan, gently heat the heavy cream until it just begins to simmer. Do not boil.

Remove the heavy cream from heat and pour it over the finely chopped dark chocolate in a heatproof bowl. Let it sit for 2 minutes, then stir gently until the dark chocolate is completely melted and smooth.

Add the unsalted butter to the chocolate mixture and stir until fully incorporated and glossy. Transfer the chocolate ganache to a shallow dish, cover with plastic wrap, and refrigerate for at least 1 hour, or until firm enough to handle.