8 ounces granulated sugar
1/4 teaspoon salt
1/4 cup all-purpose flour
1/2 cup unsalted butter, melted
2 3/4 ounces fresh lemon juice
1 large egg yolk
1 1/2 cups buttermilk
3 large egg whites
Mint leaves, sprigs for garnish

Preheat the oven to 350 degrees F.

Place all ingredients except egg whites and half of the sugar in a blender.

Beat the egg whites and sugar and fold them into the cake mixture with a whisk or spatula, and pour into a buttered 8-inch square baking pan.

Set the cake pan in a larger pan and pour hot water into this pan to come half way up the sides of the cake pan.

Bake for 45 minutes until top is lightly browned. Serve with whipped heavy cream and garnish with a sprig of mint.