Place butter and sugar in a large bowl and cream until light and fluffy using a mixing device
Add eggs one at a time, mixing well after each
Gradually add milk and heavy cream, mixing well
Whisk flour with cocoa and baking powder
Gradually incorporate into the butter mixture and mix well. You should get a medium thick batter.
Carefully incorporate the berries and cherries
Pour batter into a muffin pan , each lined with parchment paper, or muffin molds greased with butter.
Bake in the oven at 350 F for about 30 minutes. Test with a toothpick for doneness.
Once the brownies are ready, allow to cool and prepare the frosting. In a small saucepan melt the chocolate, butter and heavy cream, on low heat. Stir gently until all ingredients are dissolved and the sauce thickens a little.
Allow to cool. Frost the muffins and transfer to the fridge to harden faster if preferred.