In a saucepan, heat milk with vanilla extract over medium heat. Bring it to a gentle boil, then remove from heat.

In a separate bowl, whisk together large eggs, 1 egg yolk, and sugar until well combined and smooth.

Slowly pour about ⅓ of the hot milk into the egg mixture while continuously whisking. This step prevents the eggs from scrambling. Once well mixed, add the remaining milk and continue to whisk.

Pass the custard mixture through a fine sieve into heat-proof jars/glass/ramekins to ensure a smooth texture. Dust the top of each ramekin with a pinch of cinnamon powder.

Cover each ramekin tightly with aluminum foil. Set them into a steamer over boiling water and steam on high heat for 3-4 minutes.

Once steamed, transfer the ramekins to a wire rack to cool to room temperature. Afterward, refrigerate for at least 2 hours to set the custard properly before serving.