New to baking and live at ~5500 ft. Has anyone tried this successfully with high-altitude modifications? If so, what did you do?

Yes, I suspect that the additional time is related to your elevation. Cheers to you for your great success!

Thanks for the help everyone! I used Cynthia's recommendation and it turned out beautifully. It did take an extra ~7 minutes for the cake tester to come out clean, not sure if that's related. But I brought it to a "sparkle party" where it got a lot of compliments and went perfectly with all the bubbly drinks!

A lovely cookbook called Pie in the Sky has a wide range of recipes with instructions for various heights. The recipes are good, and the charts make it easy to adapt your own favorites.

Hi Kate! I'm in Colorado too. Let me know how it goes. I am always hoping for more patience when it comes to baking, altitude and precision.

Thanks, Cynthia! Where do you get such precise numbers? I would love to know your source.

For you elevation, increase the flour by 7%, add an extra egg, and decrease the leavening by 44%

Kate, I'm not familiar with high-alt cooking myself. But if you do a Google search on "Cooking at a high altitude" you'l get plenty of answers.