Used Colby cheese instead of aged cheddar, and came out perfect. I just came back from three weeks in Brazil so I've tasted pão de queijo from different regions. Aged cheddar would have made this on the stronger side, so a mix of parmesan and a mild soft cheese worked best for me.
Baked for 24 minutes for the first batch and 21 minutes for the second. 21 minutes was better - I wanted this on the softer side, and I think my oven runs hotter anyway. I reckon it kept cooking for a minute or two after pulling out of the oven anyway.
