Preheat your oven to 375°F / 190°C. Lightly coat a 9-inch springform pan with cooking spray and set aside. 2.
In the bowl of a food processor, combine the mashed sweet potato, 1 cup (240 ml) of the sugar, almond flour, cocoa powder, and salt.
Blend for about 30 seconds, scraping down the sides of the bowl as needed, until the mixture is completely smooth. 3. Separate 3 of the eggs.
Place the 3 egg whites into the clean bowl of an electric mixer.
Add the 3 egg yolks plus the remaining 1 whole egg to the sweet potato mixture in the food processor and pulse briefly just to combine.
Transfer this chocolate-sweet potato mixture to a separate large bowl. 4.
Using the electric mixer, beat the egg whites on high speed until soft peaks form. Gradually add the remaining ½ cup of sugar and continue to beat for 2 more minutes, or until the whites are stiff, glossy, and hold their peak. 5. Gently fold about one-third of the beaten egg whites into the sweet potato mixture with a spatula to lighten it up. Carefully fold in the remaining egg whites until just combined, being careful not to overmix.
Pour the batter into your prepared springform pan. 6.
Bake for 45 minutes, or until a toothpick inserted into the center of the cake comes out clean.
Let the cake cool in the pan on a wire rack for 10 minutes.
Then, carefully run a knife around the edge and remove the springform sides. Allow the cake to cool completely. 7. To make the glaze, melt the bittersweet chocolate in a small saucepan over medium-low heat, stirring frequently.
Once melted, remove from heat and stir in the milk until smooth.
Spread the chocolate glaze evenly over the top of the cooled cake.
Let it stand until the chocolate has set before slicing and serving.