01 - Preheat oven to 425°F (220°C). Generously butter four 6-ounce ramekins and lightly dust with flour, tapping out excess.
02 - Place chopped chocolate and butter in a heatproof bowl set over simmering water. Stir continuously until melted and smooth, then remove from heat and blend in whole milk.
03 - In a separate bowl, vigorously whisk eggs, egg yolks, and powdered sugar until the mixture is thick and pale.
04 - Gently fold the melted chocolate mixture into the whipped eggs until evenly combined.
05 - Sift flour, ground cinnamon, and salt over the batter. Carefully fold until just combined, ensuring no dry streaks remain.
06 - Evenly distribute the batter among the prepared ramekins.
07 - Transfer to preheated oven and bake for 11 to 12 minutes, until edges are set but centers remain soft.
08 - Remove ramekins from oven, let cool for 1 minute, then gently run a knife around the edges and invert onto plates.
09 - Dust with powdered sugar and serve immediately. Accompany with vanilla ice cream or whipped cream if desired.