Troubleshoot this dessert experiment

This afternoon, I made this recipe:

http://www.cooks.com/rec/doc/0,1813,152187-245199,00.html

I made one change. I used a Betty Crocker Cinnamon Swirl cake mix instead of a yellow cake mix, which means I omitted the separate cinnamon.

The results? Disappointing. The apples stayed fairly crunchy, even after I cooked it longer than the suggestion and the “crumbly mixture” had that gritty, unmixed sugar texture.

The flavors weren’t bad, but the textures were just wrong.

Where did I go wrong?

I just stumbled across another variation on the recipe which used two cups of sour cream and two eggs. Would that have helped?

I used Granny Smith apples because that’s what I had. I know they are crisper than some apples. I sliced them very thin, thin enough that you could read through the slices, but they stayed crisp. Would a different apple variety have helped?

Help!

Difficult to say, as there doesn’t appear to be a description of the desired end result. It sounds like it ought to be quite dry when it turns out.

Granny Smiths are pretty dense and hard apples. You can cook them lightly in just a splash of water in a pan (maybe some sugar too) until they start to soften

Just an FYI–I haven’t gone to your link because I’m on my phone–but I’ve never tried a recipe from cooks.com that wasn’t utter garbage. That site is a culinary black hole.

Granny Smith apples are generally regarded as being one of the best apples for baking, so I don’t think that was your problem.