Preheat your oven to 350°F (175°C) and line an 8x8-inch baking dish with parchment paper.
In a large mixing bowl, combine the mashed sweet potatoes, rolled oats, almond butter, honey (or maple syrup), vanilla extract, cinnamon, baking powder, and salt. Stir until well combined.
If using, fold in the chopped nuts or chocolate chips until evenly distributed.
Pour the mixture into the prepared baking dish and spread it out evenly with a spatula.
Bake in the preheated oven for 25-30 minutes, or until the edges are golden brown and a toothpick inserted in the center comes out clean.
Allow the bars to cool in the pan for about 10 minutes, then lift them out using the parchment paper and let them cool completely on a wire rack before cutting into squares.