Simo and Cicci recommend

Consume the Warm Soft-Centered Chocolate Cake immediately to enjoy it at its creamiest. You can store them raw in the freezer for up to 3 months.

You can use milk or white chocolate as a substitute for dark chocolate.

For a gluten-free cake, use gluten-free flour and cocoa without gluten traces.

For a lactose-free version, use lactose-free butter or plant-based butter.