Preheat your oven to 350°F.
In a medium bowl, whisk together the sugar, egg, oil, coffee, vanilla, and salt until smooth.
Sift in baking soda, flour, and cocoa powder. Stir gently.
Pour in the warm buttermilk and mix until batter is smooth and thick.
Line 4 cups with tulip liners (or 6 with regular ones) and fill with batter nearly to the top.
Add chocolate chunks on top of each filled muffin cup.
Place muffins in the oven and increase heat to 425°F. Bake for 7 minutes.
Reduce heat to 350°F and bake for an additional 10–12 minutes until a toothpick comes out clean.
Allow muffins to cool for 10 minutes in the pan.
While muffins cool, heat cream and pour over chopped chocolate. Let sit, then stir until smooth.
Use a paring knife to cut out centers and pipe ganache into each muffin.
Enjoy warm or at room temperature.
