Hi! how much fondant do I need to cover a 11x15 cake?
According to the Wilton Fondant Coverage Chart (http://www.wilton.com/cms-fondant-coverage-chart.html), for a 4 in. tall 11x15 diamond cake, you need 36 oz. fondant. I'm guessing your cake is not diamond-shaped, but I think that amount would still be accurate? I always like to overestimate the amount of fondant by a few ounces just in case, so maybe shoot for 40 oz. fondant.