Preheat the oven to 350 degrees F. Grease a 10-inch ovenproof skillet with the butter.
In a medium bowl, whisk together the buttermilk, vanilla bean paste and eggs. In a separate medium bowl, combine the flour, cornmeal, maple sugar, baking soda and salt. Stir in the buttermilk mixture until smooth.
Line the blackberries in the buttered skillet, then pour the batter over the top. Pour the cream into the center of the batter. Bake until the top crust is golden brown, 40 to 45 minutes.
Serve warm with blackberries, maple syrup and whipped cream.