In a heatproof bowl set over a pot of simmering water, melt 4 ounces of semisweet chocolate, bittersweet chocolate, heavy cream, and hazelnut spread. Stir together until melted. Remove from heat and chill in the refrigerator for 30 minutes or until the mixture firms up a bit. You want it firm but easy to work with.
*Nutritional information is an estimate. Please consult a doctor or nutritionist for the most accurate nutritional info.