Disaster Muffins

I love carrot cake and cream cheese. I've been holding onto this recipe for months. For some unknown reason, instead of this:
















mine turned out like this:




ugh. Looks aside, they're heavy, sticky, and a little too sweet. I don't know what I did wrong! The only deviations from the recipe were omitting the walnuts and adding a tablespoon of flour (for high altitude). Additionally, the recipe claims to make 24 mini muffins, filling each cup 3/4 full with batter. I nearly filled the mini cups (hoping for a high crown, Ha!) and still had enough batter left for 6 regular large muffins. The cream cheese just oozed on top, instead of descending into the muffin. I blame the recipe. What a disappointment. Maybe I can mold them into some sort of giant bread pudding thing.