Start with the ganache filling. In a small saucepan, combine the cream, sugar and salt. Heat over low heat, stirring until the sugar and salt have dissolved. Crank up the heat and scald the cream. To a heatproof bowl, add the chopped dark chocolate. Pour the scalded cream on top of the chocolate and leave to sit on the countertop undisturbed for a couple of minutes. Then stir to a smooth and shiny ganache. Chill the ganache in the freezer until hard and cold.
NOTE: if the chocolate doesn't completely melt, place the bowl in a bigger bowl with hot water or warm the ganache in the bowl of a double boiler, until all of the chocolate has melted.
Preheat the oven to 200°C or 400°F (standard oven setting) and line a muffin tin with 8 muffin cups.
Once the ganache has hardened, start with the muffin batter. In a medium-sized bowl, whisk together the milk, coffee, oil, egg and vanilla. In another bowl, stir together the flour, sugar, cocoa powder, baking powder, baking soda and salt. Add the dry ingredients to the wet ingredients and whisk to a smooth batter. Whisk in the chocolate chunks.
Spoon the batter into the muffin cups, filling each cup half full.
To a small bowl, add the 2 extra tablespoons of flour. Take the hardened ganache out of the freezer and, using a spoon, scrape out about ½ a tablespoon's worth of ganache. Quickly roll it into a ball with your hands and toss it in the flour. Then add the ganache ball to one of the muffin cups. Make 7 more ganache balls, one for each remaining muffin cup.
Spoon the remaining muffin batter on top of the ganache balls, covering it, and bake the muffins for 20 minutes, or until a tester inserted into the side of the muffins comes out clean.
For the ganache topping, scald the cream and sugar and pour it over the chopped, dark chocolate. Stir to a smooth ganache. Drizzle the hot, unsalted ganache over the muffins and sprinkle some sea salt flakes on top.
Serve warm with a big cup of tea!
Recipe by The Tough Cookie at https://thetoughcookie.com/2013/10/27/double-chocolate-muffins-with-a-salted-chocolate-heart/