Preheat oven to 350F. Line a baking sheet with parchment paper. In a small, microwave-safe bowl, combine cherries and 1 tbsp balsamic vinegar and microwave for 30 seconds, until hot. Set aside to cool.
Whisk together flour, baking soda and salt in a small bowl. In a large, microwave-safe bowl, melt the butter in the microwave. Stir in cocoa powder and sugars and mix until well blended. Stir in yogurt, remaining balsamic vinegar and vanilla extract. Add flour and mix until just combined. Stir in cherries.
Drop tablespoonfuls of batter onto a parchment lined baking sheet. Press down slightly to flatten.
Bake at 350F for 9-12 minutes or until set and slightly firm at the edges. Allow to cool on the pan for a few minutes before transferring to a wire rack to cool completely.