Preheat oven to 375 degrees F.

Make the biscuits. Combine the flour with salt, baking powder, powdered sugar, and cinnamon. Use a pastry blender or your hands to mix the butter into the dry mixture. Once the mixture resembles coarse sand, add the buttermilk and vanilla, mixing just until combined. Wrap in plastic wrap and chill until ready to use.

Prepare the filling. Toss together the cherries with blueberries, brown sugar, granulated sugar, cinnamon, nutmeg, vanilla, salt, and cornstarch. Pour the mixture into a 9x13 baking dish.

Dust a clean work counter with flour. Transfer the biscuit dough on the counter and roll out the dough until it is a ½ inch thick. Use 1 ½ inch biscuit cutter to cut 15 biscuits, using the scraps if necessary. Lay the biscuits on top of the berry filling in 3 rows with 5 biscuits in each row.

Brush the tops of the biscuits with a general amount of melted butter. Sprinkle cinnamon sugar on top and bake for 50 minutes – 1 hour or until the filling is bubbly and thick and the biscuits are golden brown. Remove from heat and let cool slightly. Serve warm with vanilla ice cream.