Instructions

1. Preheat oven to 400F.
2. Place ramekins on parchment-lined baking sheet.
3. Brush four 7-ounce ramekins generously with butter, then coat with granulated sugar.
4. In saucepan, whisk milk with cornstarch.
5. Add salt and bring mixture to simmer. Cook, stirring, until thickened, 1 to 2 minutes.
6. Add chocolate and instant coffee. Whisk until well blended (mixture will separate).
7. Whisk in yolks one at time, then add sour cream. Allow mixture to cool slightly.
8. Place ingredients in large mixing bowl and allow to cool slightly.
9. Coat clean mixing bowl with lemon juice and kosher salt. Rub lemon around bowl to remove all grease. Wipe thoroughly with paper towels.
10. Using hand mixer, whisk whites in mixing bowl until frothy, about 2 minutes.
11. Add cream of tartar; whisk until soft peaks form.
12. Add 1/3 cup granulated sugar; whisk until medium peaks form, about 5 minutes. Set aside.
13. Gently fold half of whipped egg whites into chocolate mixture.
14. Repeat process with other half of egg whites.
15. Pour batter into prepared ramekins.
16. Bake 12–14 minutes until soufflés rise but centers are still slightly liquid.
17. Dust lightly with powdered sugar.
18. Serve immediately.