So I made a batch of white chocolate ganache on Friday, I used 3 parts white chocolate and 1 part cream, and i let it set in the fridge over night but the next morning it was still so runny.. So I put it back in the fridge overnight again, and it's still runny? What did I do wrong?

Try adding more chocolate.

Did you make sure both "parts" were done by weight? Everyone keeps reiterating this. Do BOTH chocolate and cream by weight....

What did you use for white chocolate? White chocolate chips are not white chocolate and I had a horrible time trying to make ganache with then. Instead use the Bakers white chocolate or the good stuff, Merckens, coveture etc. I just bought some Guittard white chocolate at William Sonoma. I'm afraid to even use it, it was so expensive