Wash and dry the sweet potato thoroughly. Pierce it in several places with a fork, wrap it loosely in aluminum foil, and place it on a baking tray. Bake in a preheated oven at 200°C (390°F) for 45–60 minutes, until completely soft and easily pierced with a knife.

Once slightly cooled, peel and mash the flesh until perfectly smooth. Measure out 250 g of purée for the recipe.

Note: Make sure the sweet potato is thoroughly baked and very soft; otherwise, the brownies may turn out dry.

In a large bowl, mix the melted butter with the brown sugar until fully combined. Add the sweet potato purée and vanilla extract, stirring until smooth and uniform.

Sift the cocoa powder over the mixture, then add the flour, baking soda, and salt. Gently mix just until combined. Fold in the chocolate chips, reserving a small amount for the top.

Spread the batter evenly into a 20 × 20 cm (8 × 8 inch) pan lined with parchment paper. Smooth the surface with a spatula and sprinkle the remaining chocolate on top.

Bake in a preheated oven at 175°C (350°F) for 20–25 minutes, until the edges are set but the center remains soft.

Note: For an extra fudgy texture, remove the brownies from the oven at around 22 minutes.

Allow the brownies to cool completely before slicing into squares. The texture firms up as the brownies cool, so never cut them while still warm.

Serve plain or with butterscotch sauce.