Preheat the oven to 350ºF. Line an 8x8 baking pan with parchment.
In a small saucepan, heat unsweetened chocolate and almond butter over medium heat, stirring until melted.
Transfer the chocolate mixture to a large mixing bowl. Whisk in the sweet potato puree and coconut oil, then whisk in the palm sugar. Next, whisk in egg, egg yolk, and vanilla until smooth and shiny.
Add the cocoa powder, flour, and salt, and fold in just until incorporated with a rubber scraper or wooden spoon.
Add the chocolate chips and fold gently to incorporate.
Transfer the batter to the prepared baking pan and spread out evenly. Bake 20 minutes, then remove from the oven and allow to cool completely before frosting.
Sweet Potato Frosting
To make the sweet potato frosting, melt the chocolate chips in 30 second bursts in the microwave, watching carefully and stirring each time to ensure it doesn’t burn. Alternatively, you could melt the chocolate over a double boiler.
Once melted, add the sweet potato puree and stir to combine. Spread warm frosting over cooled brownies and sprinkle with flaky sea salt if desired.
Brownies will keep covered in the refrigerator for up to three days, or in the freezer for up to three months.
To make sweet potato puree, wrap 1-2 sweet potatoes in aluminum foil and bake at 400ºF for 60 minutes or until soft. Remove skins and process in a food processor until smooth, adding water as needed.