Preheat your oven to 350°F (175°C) and line an 8x8-inch baking pan with parchment paper.

In a large mixing bowl, combine graham cracker crumbs, melted butter, and brown sugar until it resembles wet sand.

Press the crust mixture into the bottom of the prepared baking pan and bake for 10 minutes until lightly golden.

In a separate bowl, whisk together mashed sweet potatoes, brown sugar, eggs, evaporated milk, vanilla extract, cinnamon, nutmeg, and salt until smooth.

Pour the sweet potato filling evenly over the cooled crust, spreading it gently with a spatula.

Bake the bars for 35-40 minutes until the filling is set and edges pull away slightly from the pan.

Cool completely in the pan on a wire rack, then lift out using the parchment paper and slice into bars.