Combine the blackberries, merlot, and 1 tablespoon of sugar in a bowl, stir, cover, and refrigerate for 2 hours or overnight.

Remove mixture from refrigerator and place in a blender or food processor and process until pureed, 1-2 minutes.

Pour through a fine mesh strainer into a bowl, mashing with a spoon or spatula, to strain out the seeds.

Preheat the oven to 350 degrees F, and line mini or standard muffin tins with liners.

Combine flour, cocoa powder, sugar, baking soda, and salt in a the bowl of a stand mixer and mix well.

Add the butter, eggs, and vanilla and beat on medium speed for one minute. Scrape the sides of the bowl and add the 1/2 cup of the blackberry merlot mixture. Mix until the batter is smooth, about 30 seconds.  Use a cookie scoop or tablespoon to fill lined muffin tins.

Bake 18-22 minutes for standard size, or 11-13 minutes for mini size, or until a toothpick inserted into the center comes out clean.

Allow the cupcakes to cool in the pan for 1-2 minutes before removing them to a rack to cool completely before frosting.

Place one inch of water in the bottom of a pot, and bring the water to a simmer. Combine egg whites and sugar in a bowl fitted over the pot, and bring mixture to 150 degrees F, whisking constantly.

Transfer mixture to stand mixer bowl, fitted with a whisk attachment and beat on medium speed until mixture cools and doubles in volume, about 10 minutes.

Add butter in one piece at a time, mixing to incorporate after each addition. Continue mixing until smooth.

Add the salt and vanilla and mix to combine. Add the remaining 1/2 cup blackberry merlot mixture and mix to combine.

Use a spatula to put frosting into a piping bag, or apply directly to the cupcakes with spatula.