Keep in mind, you want to make your chocolate layer thick enough so it doesn't shatter when it comes out of the mould, but thin enough that it doesn't overpower the filling. You should add enough chocolate that you can no longer see the mould through the chocolate. You also want to make sure your chocolate layer is even, which is why I recommend using a pastry brush to layer it onto your moulds. Using a brush will also help with ensuring you get chocolate on the sides of the moulds.