In a large microwave-safe bowl, add in the butter and dark chocolate.
Microwave in 30-second intervals, stirring in between until both the chocolate and butter have melted.
Pour the chocolate mixture into the bowl of a stand mixer, add in the powdered sugar and use the whisk attachment, on medium/low speed, to whisk until combined.
Add in the egg, salt, and vanilla extract and whisk again.
In a separate small bowl, sift the cocoa powder and ap flour together.
Add the dry ingredients to the wet and use a rubber spatula to combine.
Line a small tray, plate, or baking sheet with parchment paper and use a medium (1.5 tablespoon) spring loaded cookie scoop to scoop out 16 cookies.
The dough will be quite soft.
Carefully roll the balls of dough between the palms of your hands to make small chocolate balls.
Use a teaspoon sized measure to press a small indentation into the center of each chocolate ball.
If there are large cracks, simply press them back together but it is ok if they have smaller cracks.
They can be close together because they will chill in the fridge first.
Place the tray of cookies in the fridge for 1 hour. While the cookies are chilling, preheat the oven to 350 F (180 C) and place a rack in the middle of the oven.
Once the cookies have chilled, transfer them to a half size baking sheet lined with parchment paper or a silicone baking mat.
Space the cookies evenly on the baking sheet.
Use a spoon to scoop approximately 1 teaspoon of tart cherry jam into the center indentation of each cookie.
Bake the cookies in the preheated oven for 10-12 minutes rotating the pan after 6 minutes to ensure even baking.
The cookies should still be shiny but they will look slightly dried where they have cracked.
Once baked, remove the baking sheet from the oven and place on a wire rack to cool completely.
If you want to add the cherries, press one into the jam center of each cookie immediately after taking them out of the oven.
Once cooled they can be dusted with a little extra powdered sugar.
Store in an airtight container at room temperature for up to a week.