These cook quickly, I would recommend that you try the first batch at 9 minutes and see how hot your oven is and then adjust accordingly. You want them to be cracked on top and lightly browned on the bottom.

Also, I find that the smaller you make these the better they are. I enjoy making them big enough for one or two bites. Adjust the spices to taste. I like really snappy, gingery cookies and usually put 1.5-2 tsp ginger in my cookies.

My grandmother used to add rum to the bottom layer.
Beware any nanaimo bar recipes that suggest using vanilla pudding mix in the middle layer. That’s so wrong it makes me want to cry.

Try cutting the squares when the top chocolate layer is firm but not hardened completely – this will prevent the top from cracking when you try to cut it.