01 -
Preheat oven to 350°F (175°C). Line a 12-cup muffin pan with paper liners.
02 -
In a medium bowl, whisk together flour, baking soda, salt, and cocoa powder until well mixed. Set aside.
03 -
In a large bowl, whisk melted butter and brown sugar until smooth. Add eggs one at a time, beating well after each addition. Mix in vanilla extract, buttermilk, and mashed blackberries until incorporated.
04 -
Gradually fold the dry ingredients into the wet mixture until just combined. Avoid overmixing for best texture.
05 -
Slowly stir in hot coffee or boiling water until the batter is smooth and pourable.
06 -
Divide the batter evenly among the cupcake liners, filling each about three-quarters full.
07 -
Place the pan in the oven and bake for 18 to 22 minutes, or until a toothpick inserted into a cupcake comes out clean or with a few moist crumbs.
08 -
Remove from oven and let cupcakes cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.
09 -
Blend fresh blackberries until smooth. Strain the purée through a fine mesh sieve to remove seeds and set aside.
10 -
In a large bowl, beat softened butter on medium speed until creamy, about 2 minutes. Gradually mix in powdered sugar, then add strained blackberry purée and vanilla extract. Mix until smooth, adding heavy cream 1 tablespoon at a time as needed. Whip on medium-high speed for 3 to 4 minutes for a fluffy texture.
11 -
Once cupcakes have completely cooled, apply blackberry frosting generously with a piping bag or spatula.
12 -
Garnish each cupcake with fresh blackberries, shaved chocolate, or edible flowers as desired. Serve at room temperature.