Preheat oven to 400 degrees F. Place a baking sheet in lower third of oven to preheat. Grease interior of 6 (4-ounce) ramekins with butter and dust with sugar.
Heat milk in a small heavy saucepan over medium-high until it boils. Reduce heat to medium-low.
Whisk together 1/4 cup sugar and 2 Tablespoons cornstarch until uniform. Add to milk and whisk. Bring to a low boil and cook 1-2 minutes, whisking continuously. Whisk in Lemon Curd and lemon zest. Cool to room temperature.
In a standing mixer, or a hand mixer, fitted with a whisk attachment on high-speed whip the egg whites until soft peaks form. Add 1/4 cup sugar and continue to whisk until peaks form, but the egg whites are not dry.
Gently fold 1/4 of the egg whites into the lemon curd mixture. Continue adding egg whites 1/4 at a time until all are incorporated.
Pour lemon soufflé mixture into ramekins. Place on preheated baking sheet and bake 15-18 minutes until golden brown and soufflés have risen. Serve IMMEDIATELY, soufflés will fall in a few minutes…but are still delicious!