Preheat oven to 325 degrees F. Place flatbread rounds on a parchment lined baking sheet.
For berry topping, in a medium saucepan combine 1/4 cup granulated sugar, cornstarch, and salt. Stir in the water. Stir in 3/4 cup of the berries. Cook and stir over medium heat until thickened. Remove from heat. Add an additional 1 cup of berries and the 1 teaspoon butter, stirring until butter is melted. Gently stir in orange peel.
In a medium bowl combine mascarpone cheese, orange marmalade and vanilla; beat with an electric mixer on low to medium speed until smooth. In a small bowl stir together the 2 teaspoons granulated sugar and cinnamon; set aside..
Place baking sheet with flatbread rounds in oven for about 5-7 minutes.
While flatbread is still warm, brush with the 2 tablespoons melted butter; sprinkle with the cinnamon and sugar mixture. Spread mascarpone and marmalade mixture over flatbread rounds. Spread berry topping over mascarpone mixture. Top with the remaining berries. If desired, dust with powdered sugar.