I'd be looking at your chocolate as well - since you've switched you'll be seeing a different percentage of cocoa fats to solids, and this greatly affects the final behavior of anything made with the chocolate, but especially ganaches. The higher the cocoa fats, the more elastic the chocolate is at heart (that's why you can pour paper-thin coatings with milk or white chocolate and have them not crack, but when you try this with bittersweet or dark chocolates they fail miserably). Also, with the Callebaut, is that their couberture chocolate? Are you tempering it? If not, you might try that before adding it to your cream mixture. With the couberture chocolate types, tempering greatly improves performance and ensures a more even distribution of cocoa fats within the chocolate. This is an especially good idea when you mix two or more types of chocolate together, as you're doing with the Callebaut and Chocoa. This said, the ganache recipe I use has NEVER cracked on me, and I bake and glaze in what is substantially a desert. I've used this over caramel, over neat floured and flourless cakes, as a dip for decorative elements. It has never failed me. 10 oz black chocolate (I use a mixture of Superior 75% and Mother of Chocolate, which is something like 95% cacao solids - both of these are local, non-export products, unfortunately.) 3 tbsp butter 250 mL cream of the cream (nata; I guess that would be heavy cream in North America) Melt and temper the chocolate. Bring the cream to its scald point, then add the chocolate all at once and whisk until completely blended. Then add the butter in smallish lumps and whisk until incorporated. I normally add a bit of brandy to mine when glazing my chocolate cakes, and leave it neat for other uses.