Preheat the oven to 350°F. Line a 12-hole muffin tin with paper muffin liners and set aside. If you don't want to use liners, make sure to coat each hole in the muffin tin with non-stick cooking spray.
MIX THE DRY INGREDIENTS: Add the flour, sugar, cocoa powder, baking powder, and salt to a large mixing bowl. Whisk until well combined and set aside.
MIX THE WET INGREDIENTS: In a smaller bowl, add the milk, oil, egg, and vanilla extract. Whisk until well combined.
COMBINE ALL INGREDIENTS: Pour the wet ingredients into the bowl with the dry ingredients. Mix with a rubber spatula until just combined. Fold through the halved cherries.
SCOOP THE MUFFINS: Divide the muffin batter between the muffin liners. A muffin scoop works great for this! The cups should be about 3/4 full. If you want to add a few extra halved cherries on top, sprinkle those on right before baking.
BAKE THE MUFFINS: Bake for 20 minutes, or until cooked through. (The muffins are cooked through if they spring back when lightly touched in the middle. The muffins can also be checked with a skewer or toothpick. Insert the skewer or toothpick into the center of a muffin. If the skewer or toothpick comes out clean, the muffins are done.) Allow to cool in the muffin tin for 5 minutes, before transferring to a wire cooling rack to cool completely.