I am making a gluten Free chocolate lava cake. It calls for 5 oz of melted Dark chocolate. I don't know if I should use bittersweet chips, a dark chocolate bar, such as Giradelli's, Nestle's, Dagoba, or even Hershey's. I don't know which percentage of cocoa, 60 %, 70%, etc. has anyone else ever made one, and with what success. Thank you.