1️⃣ Preheat oven to 350°F (175°C). Line a cupcake pan with liners.
2️⃣ In a bowl, whisk flour, cocoa powder, baking soda, and salt.
3️⃣ In another bowl, mix melted butter and brown sugar until smooth. Add eggs and vanilla, then stir in mashed blackberries.
4️⃣ Alternately add dry ingredients and buttermilk, mixing gently. Stir in hot coffee until just combined.
5️⃣ Fill cupcake liners ¾ full and bake for 18-20 minutes or until a toothpick comes out clean. Let cool completely.
6️⃣ For the frosting, beat butter until creamy. Add powdered sugar, blackberry puree, and vanilla. Beat until fluffy, adding cream if needed.
7️⃣ Pipe frosting onto cooled cupcakes and enjoy!

✨Tip: Garnish with a fresh blackberry or a drizzle of melted chocolate for an elegant touch!