1 cup plain yogurt (greek style, pref.)
3 large egg yolks
3 large egg whites, room temperature
3 tbsp all-purpose flour
1/8 tsp salt
1 tsp vanilla extract
1/8 teaspoon cream of tartar
1/4 cup sugar
butter and sugar, for ramekins
Preheat the oven to 375F.
Pour the yogurt into a cheesecloth-lined strainer for about 15 minutes before using to thicken it up and drain off excess liquid.
Butter six 6-oz. ramekins. Pour a small amount of sugar into each and roll the ramekins to coat (just like flouring a pan). Set on a baking sheet.
In a large mixing bowl, whisk together yogurt, egg yolks, flour, salt and vanilla extract.
In a medium mixing bowl, beat egg whites and cream of tartar until foamy. Gradually stream in sugar and continue beating on medium-high speed until all sugar has been incorporated and egg whites have reached soft peaks.
Working in two or three batches, gently fold egg whites in to yolk mixture. This can be done with a whisk or with a spatula. Make sure all egg whites have been fully incorporated.
Divide mixture evenly into ramekins, using about 1/2 cup in each and leaving ramekins on the baking tray.
Bake for about 15 minutes, until evenly risen and lightly browned around the edges.