Combine berries and water in a small saucepan over medium heat.  Stir until the berries soften then mash with a fork or masher; about 5 minutes.

Transfer mixture to a strainer. Press berry pulp against the strainer to separate the seeds.  You should have approximately 1 cup juice. Discard seeds.

Place ¾ cup juice back in the saucepan.  Add sugar and cook over low heat.

Combine remaining ¼ cup juice and corn starch in a small bowl.  Stir until cornstarch is completely dissolved.  Add cornstarch mixture to saucepan, increase heat to medium and stir frequently until mixture comes to a boil; about 4 minutes.  Remove from heat and let cool.

While sauce cools, prepare coffee whipped cream.
Combine 1 cup heavy whipping cream, coffee and 3 tablespoons confectioner’s sugar in a small saucepan over low heat. Whisk slowly until coffee granules dissolve.  Do not boil; about 5 minutes.  Remove from heat and let cool completely.

Place remaining 2 ½ cups heavy whipping cream and remaining 3 tablespoons confectioner’s sugar in the bowl of a stand mixer. Whip with whisk attachment on medium speed until stiff peaks form. Add coffee mixture in a slow stream, mix on low or fold in with a spatula until mixed well.  Transfer to a large piping bag or a freezer bag.  Refrigerate for 30 minutes.

Slice conchas in half with a serrated bread knife. Pipe coffee whipped cream generously, drizzle with berry sauce, cover with top half of bread and drizzle with more berry sauce.  Decorate with berries.  Repeat with remaining ingredients. Serve.