Put the chocolate, cream, and butter in a big microwave-safe bowl (this is going to make almost a litre of filling, so plan accordingly). Cover and microwave for about a minute and then stir until more or less smooth. Stir in coffee granules and cherry syrup. Microwave another 30s to 1m until the chocolate is warm, but not hot. Stir until actually smooth. Pour into pie crust. Stick in fridge for about 10m. Set cherries. Let set for about 3-4 hours.
Weirdly, depending on the specific ingredients you choose, this can be a surprisingly low carb dessert. On the other hand, it is always going to be holy shit levels of high fat. Win some, lose some.