Ok, this is embarrassing, but I'm not much of a baker and have never made a slice before!

I just made a honey and oat slice, but it stuck to the bottom and was a bit squishy.. Was it not cooked enough?? The recipe said to cook it for 15mins and it would have been in for about 30mins. It was nice and golden on top.. Not sure what I did wrong. I left it to cool before eating.. (it tasted good, but I was hoping it looked good so I could actually offer people some lol)