You may know panna cotta as a classic Italian dessert — milky white and delicate, with a texture similar to custard, only lighter. It's usually served with a fruit sauce, but here we've put the fruit inside the panna cotta, turning it a pale cherry color and giving it an intense cherry flavor. The buttermilk is an unusual addition, adding a hint of tartness to balance the sweet cherries.
You can serve the panna cotta in individual molds with a dollop of Vanilla Cherry Sauce, or in martini glasses, topped with a fresh cherry. This is a make-ahead dessert that keeps in the refrigerator for up to 3 days. Look for unsweetened cherry juice (usually from concentrate) in the fruit juice section of your grocery store.
Combine the cherries, cherry juice, vanilla bean and 1/2 cup of water in a medium-size saucepan and bring to a simmer over medium heat. Cover the saucepan and reduce the heat to low. Let simmer, stirring occasionally, until the cherries are very soft, about 20 minutes.
Strain the cherry liquid through a sieve into a medium-size bowl, reserving the cherries and vanilla bean. Return the liquid to the saucepan and cook over high heat until reduced to about 1 cup, about 5 minutes. Set the cherry liquid aside and let cool to room temperature.
Remove the vanilla bean from the cherries and set aside. Transfer the cherries to a blender, add the buttermilk and purée until smooth.
Strain the cherry-buttermilk mixture through a sieve into a medium-size bowl and discard any solids. Using the tip of a small knife, scrape the seeds from the vanilla bean pod and add them to the cherry-buttermilk mixture, then set it aside. Rinse and dry the vanilla bean pod and set it aside for another use.
When the reserved cherry liquid has cooled, sprinkle the gelatin on top and let it soften, about 3 minutes.
Place the heavy cream in a small saucepan and cook over medium-high heat until it comes just to a boil. Remove the saucepan from the heat. Using a rubber spatula, immediately add the gelatin mixture to the cream and stir to combine.
Strain the gelatin mixture through a sieve into the bowl containing the cherry-buttermilk mixture and whisk to blend. Discard any solids in the sieve.
Pour about 3/4 cup of the panna cotta mixture into each of 6 individual molds (such as 8-ounce custard cups or ramekins) or martini glasses. Refrigerate the panna cotta, covered, until very firm, at least 8 hours or up to 3 days.
If you want to unmold the panna cotta onto dessert plates, remove the molds from the refrigerator and let the panna cotta soften at room temperature for about 10 minutes. Run a small knife around the inside edge of each mold. Hold the bottom of the mold in a small bowl of hot water until the panna cotta loosens, about 30 seconds. Place a dessert plate on top of the mold. Holding the mold and plate together, turn them over, shaking the mold gently to release the panna cotta onto the plate. Repeat with the remaining molds.
Serve immediately, garnished with the Vanilla Cherry Sauce and/or fresh cherries.