Heat oven to 350°F (175°C). Line an 8×8-inch pan with parchment, leaving overhang for easy lifting.
Roast whole at 400°F until very tender (45–60 minutes), then cool, peel, and mash until smooth. You want 1 cup of purée.
In a large bowl, whisk sweet potato purée, coconut sugar, granulated sugar (if using), eggs, melted oil/butter, and vanilla until glossy and cohesive.
Sift in cocoa powder, almond flour (or AP flour), baking powder, and salt. Add espresso powder if using. Fold until just combined—no dry pockets, no overmixing.
Fold in chocolate chips. The batter will be thick and luscious—exactly right.
Scrape into pan, level the top, and sprinkle a handful of chips over. Add a pinch of flaky salt if you're fancy.
22–28 minutes. Look for set edges and a slightly soft center; a toothpick should come out with moist crumbs, not wet batter. Err on the fudgy side.
Cool in pan at least 30–45 minutes. They firm as they rest. Lift out with parchment and slice with a warm knife for clean edges.