Preheat the oven to 400 degrees F.
Prepare the ingredients for the tuna salad first: mix together the pouch of tuna with the mayo, celery, onion, garlic powder, and pinch of salt.
Next, prepare your bread. Start by melting 1 tablespoon of the butter in a small microwave safe bowl for about 30 seconds until melted. Next, whisk in the egg. Then stir in the almond flour, baking powder, parmesan cheese, and pinch of salt.
Microwave the mixture for 90 seconds. Remove and let sit until it’s cool enough to handle. Slice it in half.
Heat a skillet over medium heat. Add the remaining 1/2 tablespoon of butter and cook each side of the bread for about 2 minutes per side, until toasted.
Place the bread on a baking sheet and top with the tuna salad. Add the shredded cheddar cheese on top. Bake at 400 degrees for about 5 minutes, or until the cheese is melted. Enjoy!