1. Preheat the oven to 375 degrees Fahrenheit. Grease an eight-inch round cake pan with nonstick cooking spray. Cut a piece of parchment to fit the bottom of the pan. Place it in the bottom of the pan and spray it with nonstick cooking spray. Set aside.
2. Melt the butter and chocolate chips over a double boiler until it is just melted, or in the microwave, but be careful not to burn the chocolate (about one minute).
3. Add the sugar, salt, vanilla, and espresso if using and stir to combine.
4. Add the eggs one at a time and mix until smooth.
5. Add in the cocoa powder and stir until just combined. Don’t overmix.
6. Pour batter into a prepared, lined, and greased pan and bake for about 25 minutes or an instant read thermometer reads 200 degrees Fahrenheit.
7. While the cake is cooling, make the chocolate ganache. Combine the chocolate and cream in a medium microwave-safe bowl, and heat until the cream is very hot so it will melt the chocolate. I always start with 30 seconds and check it. It might take longer, it just depends on your microwave. Remove from the microwave and stir until the chocolate melts and the mixture is smooth.
8. Spread the chocolate ganache glaze evenly over the cooled cake. Let the topping set up for a few hours before cutting and serving the cake. (You can put it in the refrigerator to speed up the process.)
can I use oil?