I made a batch of the most popular ganache recipe in the Recipes section. Everything was good, up to the point when I put it in the fridge. Several posts say to leave it in there overnight, which I did. When I pulled it out, it was very hard... too hard to effectively whisk. So, I popped it in the microwave for 30 seconds and stirred, then another 20 and stirred, then another 20 and stirred, and it finally it was soft enough to spread and frost my cake. Is this normal? Should I have skipped the refrigeration part?

Second, the recipe was made with all semi-sweet chocolate. The frosting was good, but it was a little chocolate-chippy (which makes sense). I assume it is permissible to mix chocolates... maybe half semi and half milk?

Any help is really appreciated!
Z

What you got was a truffle, but no real problems. I don't generally refrigerate it over night. I whip some, chill some and repeat until it is whipped to where I want it. If you over beat it, it will separate,and you have to start over. VERY gently remelting.

It is certainly fine to mix chocolates. My mom prefers more milk to dark, but do what you like. The lighter the chocolate, the less cream you may need. If it is too thick, add hot cream. to thin, melted chocolate.