Couple of thoughts -
Your spread might be suffering from a broken emulsion - there isn't enough water to suspend the fat any more. You could try the various techniques to rehabilitate a broken emulsion and see if one would work. But if I were to try - I'd split this into a few bowls and try with only part of the mass. Can I ask what the rest of the ingredients are in there so we can make some suggestions around what to try?
When you are making a batch of chocolate in a melanger - at first it is thick, then becomes thinner as the particle size get's smaller and each particle is coated with cocoa butter. When the particle size gets even smaller then the amount of cocoa butter is no longer sufficient to coat the increased number of particles so the chocolate becomes thicker again. For this issue you add more cocoa butter. I don't think that's necessarily what's going on here but the thought did cross my mind.
Another thought - you say my 'chocolate/hazelnut paste' - is there anything else in there? Because if not this is just gianduja and I'd probably just process the nuts alone in the cuisinart to get the hazelnut paste - melt the chocolate and stir in the nut paste then temper the whole thing.
