Hello! I am very new at cake baking and I have two questions for a cake I need for Saturday. I made my cakes today, cut and filled with chocolate ganache but not needing them until Saturday I froze them.
1- Should I wait until they are defrosted before I crumb coat?
2-Also, I made my buttercream icing too runny, can I "fix" that by adding some more powder sugar?
One more thing: everytime I make my chocolate ganache I am left with pieces of chocolate in the ganache even thought heavy crem is hot and I make sure everything is melted...why??? the only thing I can think of is because I used chocolate chips, but they were completely melted! So, what is my problem?
Thank you for your help!

I would let the cakes thaw somewhat before crumbcoating, but then I live where it's very hot, and things tend to sweat when I take them out of the freezer. You might not actually need to do this. Yes, you can fix your buttercream by adding more powdered sugar. That's the standard remedy for this problem! And the reason you still have lumps - or lumpettes - of chocolate in your ganache is probably that you haven't mixed it long enough with the hot cream. Do you melt your chocolate beforehand? Not all recipes say to do this, but I find putting it in the microwave in 20-second bursts and stirring it in between each one makes this process work better. Good luck, and welcome to CC!