Preheat oven to 400 degrees F (200 degrees C).

Spray an 8 x 8 inch baking dish with cooking spray.

Microwave the diced sweet potato for 3-5 minutes to soften.

In a large bowl, combine the cooked sweet potato, drained black beans, drained diced tomatoes, chopped onion, chopped bell pepper, chili powder, garlic salt, and cinnamon.

Spread 1/2 cup of salsa on the bottom of the prepared baking dish.

Arrange tortilla strips on top of the salsa to cover the bottom of the dish.

Spoon a layer of the sweet potato/black bean mixture over the tortilla strips.

Spread the remaining 1/2 cup of salsa over the sweet potato/black bean layer.

Add another layer of tortilla strips.

Add the remaining sweet potato/black bean mixture.

Top with shredded cheese (optional).

Bake uncovered for 20-25 minutes, or until the cheese is melted and the top is slightly browned.

Let stand for 5 minutes before cutting into squares and serving.

Serve with additional salsa, cilantro, and/or avocado, if desired.