Preheat the oven to 300 F (150 C). (I baked my cake on 320 F.) I lined a 9 inch cake pan and sprayed the pan and the parchment paper before pouring the batter into it. If you use muffin pans, line them with the cupcake holders.
Put the semisweet chocolate in a medium bowl with hot coffee. Let it stand, stirring occasionally until the chocolate melts and the mixture is smooth. I used semi-sweet chocolate chips as I was out of semi-sweet chocolate pieces and I used espresso coffee.
In another medium bowl, whisk together the sugar, flour, cocoa powder, baking soda, baking powder, and salt.
In a separate bowl, beat the egg until it is pale yellow. Add the oil, yogurt, and vanilla, beating well.
Gradually pour the melted chocolate mixture into the egg mixture and beat till it combines thoroughly.
Add all the dry ingredients in three portions and beat on low speed until the batter is just combined. With a spatula, scrape down the sides of the bowl and briefly stir to make sure all the dry ingredients are absorbed.
Spoon the batter into the lined cake pan and bake for approximately 35-40 minutes or until a toothpick inserted in the middle comes out clean.
Spoon the batter into the lined cake pan and bake for approximately 35-40 minutes or until a toothpick inserted in the middle comes out clean.
Melt the bittersweet (or semisweet)chocolate in a metal or glass bowl set over a pan of gently simmering water. Stir frequently to prevent scorching. If you find the chocolate too thick, add a couple of tablespoons of water and stir until combined. When the chocolate is completely smooth, it is ready. Stir in the 2 teaspoons of light corn syrup.
Let the cake or cupcakes cool completely before frosting. You could store the cupcakes in an air tight container at room temperature.