Slice sweet potatoes lengthwise into 1/4 inch slices. Depending on the size of your sweet potato you can get 4-6 slices which is 2-3 tuna melts. Add to the toaster like you would bread and toast on high. It took me 2 rounds to get it cooked how I like with a little bit a browning on both sides.
Usually my sweet potato toasts brown more on on side, whatever side they are browned more on, place it brown side up to assemble your melt.
In a small bowl combine 1 can of Safe Catch tuna, mayonnaise, garlic powder and salt and pepper to taste. Scoop some onto the sweet potato toast (amount depends on size of the potato), followed by some cheese, then another toast.
Place a pan over medium low heat and let it get warm.
Place tuna melt, cheese side down in the pan and cover.
Cook for about 1-2 minutes until cheese is melted, then turn over and cook for another 30 seconds – a minute.