Crumble the chocolate cake as finely as possible.
Divide into two bowls if you wish to offer two different flavours.
Add salted butter caramel to one bowl, and praline, gianduja or a spread of your choice to the other. Mix well to obtain a homogeneous texture. You should be able to shape the mixture into balls easily.
Fill the cavities of the popcake mould. If you don't want to use a mould, you can shape the balls by hand. In this case, weigh each ball so that all pop cake balls are of equal size, about 25 g each (0.8 oz)
Add a hazelnut to the center of each ball half. Top with a little crumbled cake and smooth the surface. Both cavities must be filled to the brim and smoothed.
Close the mold and press lightly to weld the two parts together.
Turn out the cake pops and repeat with the remaining crumbled cake.
If you wish, you can make a small hole in one half of the ball and add a little salted butter caramel.