Preheat oven to 350 degrees.

In a large pot over medium heat, melt two sticks of butter. Once butter begins to brown, add prunes, brown and granulated sugars, miso paste, and vanilla extract. Bring to a boil and boil for about 3-4 minutes. Remove from heat and add to a food processor and blend for 20 seconds.

In a large mixing bowl, combine flour, baking powder, cornstarch, and salt. Whisk together and then add prune mixture to dry ingredients. Lightly fold together and then add eggs and water. Continue to mix until ingredients are incorporated.

Spray an 8x8 square pan and line with parchment paper. Add batter and bake for 25-30 minutes. Allow to cool.

Melt chocolate according to package instructions. Add to a piping bag (or use a spoon) and drizzle chocolate over blondies.