Bake the sweet potato (unpeeled) in the centre of the oven at 400 F/ 200 C/ gas mark 6 for 30-40 minutes, until fork tender. Remove from the oven, peel and scoop out the pulp. Puree with the maple syrup and set aside.
Preheat the oven to 350 F/ 180 C/ gas mark 4. Lightly grease a 23 cm square baking pan and line with parchment paper. Set aside.
In a large bowl combine the flour, baking powder and cocoa powder. Stir using a whisk removing any lumps and set aside.
Beat together the eggs, sugar and oil for 2 minutes until fluffy and pale. Whisk in the sweet potato/maple syrup puree.
Place the chocolate in a small bowl and microwave until 80% melted. Remove from the microwave and stir to melt completely. Gradually add into the batter folding in until well combined. Stir in the pecans.
Add the flour mixture into the batter and stir just to combine. Pour the mixture into your baking pan and smooth out the top with a spatula. Bake in the centre of the oven for 28 minutes.
Remove from the oven and set aside for 15 minutes. Lift out of the pan with the paper and place on a rack to cool completely. Enjoy!
Notes
Sweet potato: Use 2 small sweet potatoes (rather than 1 larger potato) to minimise cooking time.
Make ahead: To save time you can roast the sweet potato ahead. Once it’s cooled you can either refrigerate it for up to 2 days (unpeeled, covered) or puree with the maple syrup before refrigerating.
Chocolate: Use good quality dark chocolate (65 - 70% cocoa solids).
Cocoa: Either cocoa or cacao powders are fine to use (you might also like this collection of 27 everyday healthy cacao recipes).
Pecans: You could use another soft nut variety, such as cashews, walnuts or even macadamia. Almonds, hazelnuts or brasil nuts are ok to use too but as they are quite tough you might have to chop them a little more finely.
Batter: Do not overmix the batter. Once you've added the dry ingredients stir just to combine.
Storing: Cut into squares and store in an air tight plastic container in the fridge for up to 3 days.
Total Time includes the time needed to bake the sweet potato.