Simmer the Prunes: In a small saucepan, combine the prunes and water. Simmer over medium heat for about 10 minutes, or until the prunes are soft and the water is mostly absorbed.

Blend the Prunes: Transfer the prunes and any remaining liquid to a blender or food processor. Blend until smooth to create a prune puree.

Combine Butter and Sugar: In a large mixing bowl, whisk together the melted butter and sugar until well combined.

Add Eggs and Vanilla: Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract.

Combine Dry Ingredients: In a separate bowl, whisk together the flour, cocoa powder, baking powder, and salt.

Combine Wet and Dry Mixtures: Gradually add the dry ingredients to the wet mixture, stirring until just combined. Be careful not to overmix.

Add Prune Puree: Fold the prune puree into the batter until evenly distributed.

Pour into Pan: Pour the batter into a greased 8x8 inch baking pan, spreading it evenly.

Bake: Bake at 350°F (175°C) for 25-30 minutes, or until a toothpick inserted into the center comes out clean.

Cool and Serve: Allow the brownies to cool in the pan before cutting into squares. Enjoy the rich, moist brownies with a glass of milk or a cup of coffee.