Heat oven to 350°F. Grease a 9-inch round pan with butter and dust with cocoa. Line the bottom with parchment.
Whisk flour, sugar, cocoa powder for batter, baking powder, baking soda, and salt in a large bowl.
Combine buttermilk, oil, vanilla, and hot coffee in a pitcher or medium bowl.
Pour wet mixture into dry ingredients. Whisk just until smooth and no dry streaks remain.
Fold in chopped cherries and chocolate chips. Scrape batter into the prepared pan.
Bake 33–38 minutes, until a toothpick comes out with a few moist crumbs.
Cool in the pan 15 minutes. Turn out onto a rack, remove parchment, and cool completely.
Warm cream in a small saucepan until steaming. Pour over chopped chocolate and let stand 3 minutes.
Whisk ganache until glossy and smooth. Let thicken slightly to a pourable consistency.
Spread cherry jam over the cooled cake top in a thin, even layer.
Pour ganache over the jam-covered cake, letting it drip down the sides. Set 20–30 minutes before slicing.