How to Make It
Preheat the oven to 375°. In a bowl, using a wooden spoon, blend the Parmigiano-Reggiano with the butter and potato starch until crumbly. Sprinkle tablespoons of the mixture onto a large nonstick baking sheet and lightly press them into neat 2 1/2-inch rounds spaced 2 inches apart. Bake for 3 minutes or until smooth, pale golden crackers form. Let the crackers cool on the baking sheet for about 30 seconds, then, using a spatula, carefully transfer them to a rack to cool and crisp. Leave the oven on.
Lightly butter eight 1/3- to 1/2-cup ramekins and set them on a baking sheet. In a large bowl, whip the heavy cream until soft peaks form. Blend in the ricotta and Parmigiano-Reggiano. In a large bowl, beat the egg whites with a pinch of salt, then whip them until firm peaks form. Using a spatula, stir one-third of the beaten whites into the ricotta mixture to loosen it, then fold in the remaining whites just until blended. Spoon the soufflé mixture into the prepared ramekins; run your thumb around the inside edge of the ramekins to clean them. Bake the soufflés in the center of the oven for about 20 minutes, or until puffed and slightly loose in the center.
In a small saucepan, bring the chicken stock to a boil. In another small saucepan, bring the heavy cream to a simmer over low heat. Add the Parmigiano-Reggiano to the cream and whisk to blend. Whisk in the hot chicken stock until smooth and remove from the heat.
When the soufflés are done, turn them out onto small plates; if they don't release easily, run a thin knife around the edge of the soufflés and try again. Pour the sauce around the soufflés, top each one with a Parmigiano cracker and serve at once.