Preheat oven to 375 degrees. Line a muffin tin with muffin cups and spray with nonstick cooking spray. In a large bowl, whisk together eggs, oil, sugar, vanilla, and instant coffee.
In a separate bowl, mix together flour, cocoa powder, baking powder and soda, and salt. Mix half of the dry ingredients into the wet, then stir in half the buttermilk. Do this again with remaining ingredients and stir until just combined (don't over-stir). Gently fold in chopped berries and chocolate chips.
Pour equal amount of batter into each of the 12 muffin cups and bake for 18-20 minutes or until a toothpick comes out clean when inserted into a muffin. Let cool in the pan for 2-3 minutes then remove muffins to a cooling rack. Serve warm with a dollop of Greek yogurt and honey, or with a little butter.
Recipe by Eating Made Easy at https://eating-made-easy.com/healthy-double-chocolate-muffins/