Preheat oven to 375F. Spray a 9×5-inch loaf pan with floured cooking spray, or grease and flour the pan; set aside.
Add the sweet potato to a large mixing bowl (I microwaved the sweet potato for 7 minutes, let it cool momentarily, peeled it, and mashed it with a fork in the mixing bowl).
Add the next 7 ingredients, through optional salt, and whisk to combine. Some small sweet potato lumps will be present and that’s okay.
Add the flour, baking powder, and slowly pour the beer over the top. It will bubble and foam. Stir until combined and no white bits remain at bottom of bowl. Batter is thick, gloppy, and dense.
Turn batter out into prepared pan, smoothing the top lightly with a spatula. Bake for about 40 minutes, or until top is domed, firm and set, and a toothpick inserted in the center comes out clean or with a few moist crumbs, but no batter.
Allow bread to cool in pan for about 15 minutes before turning out onto a wire rack to cool completely. Slice using a serrated knife.
Notes
Storage: Bread is best fresh, but will keep airtight for up to 4 days. I prefer it toasted with butter, and makes good sandwich bread.