Preheat oven to 350 degrees Fahrenheit. Spray springform with non-stick spray
In a heavy saucepan, heat butter, chocolate, and coffee over low heat.
When chocolate is almost melted, turn off heat and gently stir until it’s all smooth. Set aside to cool.
In a bowl, whisk together eggs, sugar and vanilla.
When chocolate is cool to the touch, whisk egg mixture into chocolate until combined.
Pour mixture into springform.
Bake for 50 minutes. It will puff up. The sides will be firm and center wet.
Turn the pan and bake for 10 minutes more. Cool on wire rack until it reaches room temperature.
Remove sides of the pan, and cover with plastic wrap.
Refrigerate overnight. Let stand 45 minutes before serving