For the filling:
Heat oven to 350 degrees.
Heat a medium saucepan over moderate heat. Cook all filling ingredients, stirring occasionally, until sugar begins to dissolve, about 3 minutes. Spoon filling into a ceramic or glass baking dish.
For the crust:
Whisk together flour, sugar, baking powder and salt in a medium bowl. Mix in the butter with your fingertips until mixture resembles coarse meal. Stir in buttermilk and heavy cream with fork until just combined (do not over mix). Spoon dough over pineapple cherry filling, leaving space between mounds. Sprinkle sugar on topping. Bake until topping is golden brown and fruit is bubbling, about 25 minutes. Cool slightly and serve warm.