This is my take on a Thomas Keller version -- why not start with the best? -- but I use nonfat Greek yogurt (one of my favorite ingredients) instead of sour cream. And I like a bit more structure to my panna cotta, so I upped the gelatin a bit, and I REALLY like the vanilla bean flavor and the speckles in vanilla bean paste, so I increased that too. It is tangy and light, but also luxuriously creamy. - susaneas —susaneas
Test Kitchen Notes
In a word, this was wonderful! This recipe produced a panna cotta that was dense and creamy, with only a slight hint of a tang from the Greek yogurt and buttermilk. Due to lack of a local resource for vanilla bean paste, I improvised by scraping one and a half vanilla beans, and adding a splash of vanilla. The taste was much more intense than using pure vanilla extract alone. The only suggestions I have is that the first step listed -- softening the gelatin -- be inserted between steps 2 and 3. For those of us easily distracted (by the dog, the phone, etc), this meant by the time I needed to use it, it had solidified into a solid mass of an unusable rubber-like substance. Also, I left my panna cotta in the strainer about 20 minutes before spooning it into ramekins. All in all, this recipe was easy to follow and nearly foolproof. Best of all, it resulted in one of the best panna cottas I can remember! I will definitely be making this again. —JennyInKS
Sprinkle gelatin over water in a small cup, stir and let soften.
Whisk together the Greek yogurt, buttermilk, salt, vanilla bean paste and sugar in a bowl.
Heat about 1/2 cup of the yogurt mixture in a small saucepan over a low flame, stirring, just to warm up. Stir in the softened gelatin until it dissolves. After mixture is completely smooth, stir gelatin mixture into the rest of the yogurt mixture.
Whisk the creme fraiche in a separate bowl until it thickens and holds its shape. Fold in the yogurt mixture, and then strain through a fine-mesh strainer into a bowl with a spout or a 4-cup liquid measuring cup.
Pour the mixture into 6 4- to 5-ounce ramekins. Place ramekins on a pan or tray, cover with plastic wrap and refrigerate for at least 6 hours or overnight.
To unmold, dunk each ramekin 2/3's of the way into a bowl of very hot tap water to loosen. Place a dessert plate on top, flip and give a gentle but firm shake to release.