Can I broil a box cake in the oven?
I would suggest putting the cake on the lowest shelf your oven has and put a second oven rack above it then put a baking sheet or hotel tray on the upper rack to block direct radiation. If you have an oven steel or pizza stone, you can put that under your cake while you're preheating to help with the bake (leaving it in). It will hold a lot of heat and make the cook more even.