Preheat oven to 350 degrees and line a baking sheet with parchment paper. In a large bowl, using an electric hand blender, combine together the eggs, oil and water. Slowly add the brownie mix and flour blend until a dough forms.
Roll out dough into tablespoon sized balls and line on parchment paper. Freeze dough for 5 minutes, then bake for 10-12 minutes until the brownie cookies are firm to the touch. Cool completely on a wire rack.
In a medium sized bowl, blend the butter using an electric hand blender until smooth. Add the pureed berries and mix until incorporated. Slowly blend in the frosting mix and whisk together until smooth.
Place frosting in a piping bag or plastic storage bag. Cut the tip off of the end of the bag and carefully pipe the frosting onto the bottom, flat side of a brownie cookie. Top with a second cookie. Repeat with remaining cookies and frosting.