Ah, I just re-read one of your posts when I checked the recipe.
"Here's the recipe I used (except for the cream part, I used all milk):"
That's where you went wrong. You can't use all milk, milk doesn't have as much fat as the cream. Believe it or not, that small chemical difference is all that it takes to change the chemistry of that batter. All milk made the batter leaner and wetter so the tiny air pockets collapsed on each other as the cake baked.
Thanks everyone for taking the time to reply to this. This was a new recipe for me and when I had to rebake it I had to go back to the store for more cake flour and decided to get the heavy cream too. The second try came out much better.
I will also remember to double-check my leavening agents going forward. When I tripled the recipe I could have mis-measured.
I appreciate everyone's replies and help. I love Cake Central!