Preheat oven to 350°F (175°C). Line 12 standard muffin cups with paper liners.
In a medium bowl, sift together flour, granulated sugar, cocoa powder, baking powder, and salt.
In a separate bowl, whisk butter until smooth. Add eggs one at a time, beating well after each. Mix in buttermilk and hot coffee/water.
Gradually combine the wet and dry ingredients in batches using a spatula, folding gently to maintain lightness.
Fill each prepared liner 3/4 full with batter. Bake 20-25 minutes until a toothpick inserted comes out clean.
Meanwhile, in a bowl, toss cherries with granulated sugar and lemon juice. Chill for 15 minutes.
In another chilled bowl, whip heavy cream and vanilla extract with a handheld or stand mixer until stiff peaks form (about 4-5 minutes). Add additional sugar to taste if needed.
Remove baked mini cakes from oven and let cool completely. Place a few cherry halves in each cup, top with whipped cream, and store in refrigerator until serving.