Dissolve all but 1/4 teaspoon salt in large pot of boiling water. Add peas. Blanch 2 minutes. Drain and rinse under cold water. Chill and drain thoroughly. Puree in blender or food processor the peas, mint, and sugar remaining salt and pepper until smooth. Continue to puree while adding egg whites 1 at a time. Pour in cream. Blend until combined.
Divide mixture among 6 greased 1/2 cup ramekins or custard cups. Set ramekins in baking pan. Add boiling water to pan to halfway up sides of ramekins. Cover with foil and vent. Bake in a preheated 350 degree oven for 30 minutes or until toothpick inserted in center pulls clean. Let set a few minutes. Run sharp knife around edges and invert onto serving dish. Garnish with mint sprig and dollop of sour cream or creme fraiche.