Peel the zest from 1 of the oranges in 1-inch-wide strips. In a small saucepan, combine the orange zest strips with the sugar, water, bay leaves and peppercorns and simmer over moderate heat until the sugar is dissolved. Pour the mixture into a heatproof bowl and let steep for 2 hours. Strain the syrup.
Meanwhile, in a small bowl, sprinkle 3/4 teaspoon of the gelatin over 1/4 cup of the orange juice and let stand until the gelatin softens, about 10 minutes. Scrape the orange gelatin into the small saucepan and set over low heat, stirring, until melted. Stir in the remaining 1/2 cup of orange juice. Pour the orange gelatin into wineglasses or parfait glasses and refrigerate until completely set, at least 1 hour.
In the small saucepan, combine the cream with 1/4 cup of the sugar syrup. Sprinkle the remaining 1 1/2 teaspoons of gelatin over the cream and let stand until the gelatin softens, about 10 minutes. Heat, stirring, just until melted, then pour the mixture into a glass measuring cup. Add the buttermilk and 1/4 cup of the syrup and let cool to room temperature. Gently pour the buttermilk mixture over the orange gelatin in each glass and refrigerate until very firm, at least 6 hours or overnight.
Working over a bowl, peel the oranges with a sharp knife, removing all of the bitter white pith. Cut in between the membranes to release the sections into the bowl. Stir in any remaining orange sugar syrup and refrigerate until the panna cotta is chilled. Spoon the orange sections into the glasses just before serving.
Make Ahead: The panna cotta and orange compote can be refrigerated separately for up to 2 days.
Notes: One Serving: 242 calories, 9 gm total fat, 0 gm saturated fat, 44 gm carb.