Chop the 500 g cake leftovers into a bowl. Add the 100 g jam or jelly and 60 g cocoa powder. Gradually add amaretto to taste, stirring to combine—the mixture should remain malleable and hold together. Once fully mixed, form into roughly 10 golf ball-sized balls.
Roll each ball in the 150 g chocolate sprinkles until fully coated. Place each coated ball into a paper case.
Refrigerate for at least 8 hours (preferably overnight) until the balls are solid and firm.