Begin by preparing your baking dishes. Use small ramekins because they help the souffle rise perfectly. Coat the inside of each ramekin with a thin layer of butter. After that, sprinkle sugar all around the inside so the souffle mixture can climb up the sides as it bakes.

Warm the milk in a small pot on low heat. Do not let it boil. You want it warm enough to help the mixture come together smoothly. While the milk warms, separate the egg yolks and whites into two bowls.

Mix the cornstarch and sugar with the egg yolks. Stir until you see a smooth and pale yellow mixture. Slowly pour the warm milk into this mixture while stirring nonstop. When everything is smooth, place the mixture back into the pot and cook it on very low heat. Keep stirring until it becomes creamy and thick. Remove it from heat and add the vanilla extract. Let this base cool for a few minutes.

Now focus on the egg whites. Use a clean bowl for whipping. Begin by whisking the whites until they look foamy. Add a tiny pinch of salt for stability. Continue whisking until soft peaks form. Then whisk a little more until the peaks become firm but not dry.

Once the whites are ready, gently fold one large spoon of the whites into the warm vanilla mixture. Then carefully fold the rest of the whites in small portions. Make sure you fold slowly without pressing too hard because you want to keep the air inside the mixture.

Spoon the mixture into the prepared ramekins. Fill them almost to the top. Gently run your finger around the rim to clean the edges.

Place the ramekins on a baking tray. Bake in a hot oven at 190 degrees Celsius for about 15 to 18 minutes. Keep the oven door closed while baking. When the souffle rises high and the top becomes lightly golden, it is ready. Serve immediately.