Prepare the chocolate truffle filling first. Place the chocolate chips into a large microwave-safe bowl and pour in the cream. Heat the chocolate and cream in the microwave, stirring every minute, until the chocolate is melted and smooth. This can also be done over a double boiler. Cover the resulting ganache and place into the refrigerator to cool completely. This can also be done ahead of time.

Next, prepare the crepes. If using a blender, simply place all the ingredients into the blender and pulse for 2 to 3 minutes until a smooth batter forms. Let the batter rest for a few minutes before using. To prepare the batter by hand or with a mixer, first whisk together the eggs, milk, melted butter, vanilla and sugar for 2 to 3 minutes, until smooth. Sift the flour and cocoa powder into the batter and whisk again until smooth.

Preheat a crepe pan over medium heat. Add 1/4 cup crepe batter per crepe. Pour the batter into the center of the pan, then tilt the pan around to spread the batter evenly. Cook for about 1 minute on the first side, until the batter is no longer 'wet' and 'shiny' on the top. Use a rubber spatula to turn the crepe over and cook on the other side for 30 seconds.

Stack the crepes onto a wire rack to cool completely. Don't stack the crepes directly one atop the other - stagger them to cool faster. Assemble the cake once the crepes are completely cooled.

Once the chocolate ganache is completely cooled, whisk it using a mixer on high speed for 2 to 4 minutes, until a fluffy filling forms. The filling should be fluffy but be take care not to over-mix the ganache which can cause it to separate. Because the ganache is cold, it will be on the thicker side. Spread 1/4 cup of the chocolate filling between each crepe, spreading it evenly to the edges.