Make the filling: Preheat the oven to 375 degrees F. Butter a 9-by-13-inch baking dish. Combine the cherries, granulated sugar, cornstarch, lemon juice and vanilla and almond extracts in a large bowl; toss until combined with no clumps. Spread in the prepared dish.
Make the topping: Pulse the flour, granulated sugar, baking powder and salt in a food processor until combined. Add the butter and pulse until pea-size pieces form. Pulse in the chopped chocolate. Whisk the egg with the buttermilk in a medium bowl; add to the flour mixture and pulse a few times until the dough just comes together.
Turn out the dough onto a lightly floured surface and pat into a 4-by-12-inch rectangle (about 1/2 inch thick). Cut into twelve 2-inch squares; arrange in 3 rows over the filling. Brush the tops with buttermilk and sprinkle with turbinado sugar. Bake until the topping is browned and the filling is bubbling around the edges, 45 to 55 minutes. (To check for doneness, look under a biscuit to make sure it?s not raw; continue baking if necessary.) Let cool at least 30 minutes. Serve with ice cream.