Preheat the oven to 350ºF.
Combine 1 cup of the sugar and the lemon juice in a heavy nonreactive saucepan over medium heat. Cook, stirring constantly, for about 10 minutes, or until the sugar dissolves and turns smooth and brown. Remove from the heat. Spoon 1 tablespoon of the caramel into each of four 6-ounce custard cups.
Combine the eggs, cream, vanilla, and the remaining 1/4 cup sugar in a small mixing bowl. Whisk to dissolve the sugar.
Evenly divide the mixture among the custard cups. Place the cups in a baking pan large enough to hold them comfortably. Fill the pan with enough water to reach three quarters of the way up the side of the cups.
Bake for about 1 hour, or until the custard sets and a knife inserted in the custard comes out clean. Let cool, then refrigerate for at least 4 hours.
When ready to serve, use a thin knife to loosen the custard around the edges of the cup. Invert onto chilled dessert plates.
Yield: 4 servings