This toaster:
All the heating coils are in series, so I can't cut the power to just some of the coils by adding a diode.
The bread is held in baskets that clamp the bread on the sides when it's lowered, and I tried making one side of the basket hold the toast farther from the coils on the non-Kitty side, but it didn't help.
I'm thinking of covering the non-Kitty side with a screen to block some of the heat, but I can't find a suitable non-metal material (to prevent shock hazard).