Pre-heat oven to 450 degrees F.
In a microwavable bowl, melt chocolate and unsalted butter for 30 seconds at 50% power, remove from microwave, stir with a spoon, bring back to microwave.
Repeat until all chocolate is melted.
In another bowl, whisk together egg, egg yolk, flour, and sugar.
Add melted chocolate into egg mixture. Whisk to combine.