I have made 2 bunny 3d brownies cake & the 1st one burnt at the ears & didnt cook in the middle & fell appart when I took it out of the pan I cooked it on 300 for about 45 min & kept checking the middle. the second on I cooked on 350 & filled body & when it looked like the body was almost done I added the ears. But it came out & broke at the ears & where the choc chips were it stuck to the pan ?? I sprayed it real good with nonstick spray.
Sorry this happened, I know that is frustrating. I guess I don't know what type of pan this is. Are you supposed to fill the pan in two stages? I guess I am confused. A lot of those specialty pans can be really hard to bake in because of the how deep they are in some areas and shallow in others. I am sure that is what you are experiencing. When I am not sure what temp to bake I ususally go for 325
You other option could be to just bake a sheet of brownies and carve a bunny out of it? I know it's more work, but it may be less hassle.