for the filling:
2 pounds red rhubarb, trimmed, chopped into ¾-inch pieces
½ cup sugar
2 tbs fresh-squeezed orange juice
for the shortcakes:
2 cups all-purpose flour
1 tsp baking powder
½ tsp baking soda
1/3 cup sugar
1 tbs freshly-grated orange zest
¼ cup cold butter
1 cup buttermilk
½ cup sour cream
1 cup cold whipping cream
1 tbs sugar
½ tsp orange-flower water or vanilla extract
fresh mint leaves for garnish
filling: In a large saucepan over med-low heat, combine rhubarb, sugar and orange juice. Cook, stirring gently, until mixture simmers and rhubarb is tender and somewhat jammy. Cool, then chill thoroughly.
shortcakes: Preheat oven to 400 degrees. In a large bowl, whisk together flour, baking powder and soda and sugar and orange zest. Cut in the butter until the mixture resembles coarse crumbs. In a small bowl, combine the buttermilk and sour cream. Add to the flour mixture and stir with a fork, just until combined. Scoop batter into 6 equal mounds on a Silpat or parchment paper lined baking sheet. Sprinkle with sugar and bake about 15 minutes, until golden. Transfer to a baking rack to cool.
To serve, whip cream together with sugar and orange-flower water or vanilla. Split shortcakes in half. Arrange bottom halves on plates. Spoon rhubarb filling over pastries. Garnish with whipped cream and mint leaves and replace tops of cobblers.