Melt butter and chocolate together in a double boiler or a metal bowl set over a sauce pan.
Mix sugar and cornstarch in a bowl.
When butter and chocolate are melted, add and incorporate to sugar mixture.
Mix in whole eggs and yolks just until smooth.
Cover and refrigerate overnight.
Preheat oven to 400F.
Coat ramekins with butter and sugar. Fill ⅔ with batter.
Set on cookie sheet and bake 20-24 minutes. Center will crack slightly when done and should remain gooey. It's normal for the soufflés to fall when cool.
Serve with ice cream or whipped cream.
Recipe by The Taste Edit at https://thetasteedit.com/chocolate-souffles/