Savory muffins built on roasted sweet potato, parmesan, thyme and black pepper, with no sugar at all. A tight tender crumb and a browned parmesan cap on every top.
Prick 1 pound of whole sweet potatoes and roast on a foil lined tray at 400F for 50 to 60 minutes, until collapsing and leaking dark syrup.
Split them, scoop out the flesh, and mash smooth with a fork. Measure out 1 ¼ cups and let it cool.
Mix the Batter
Heat the oven to 400F and line a 12 cup muffin tin with paper cases.
Whisk the flour, baking powder, baking soda, salt, mustard powder, smoked paprika, and black pepper together. Stir in 1 cup of the parmesan and all the herbs, keeping ¼ cup of cheese back for the tops.
In a second bowl, whisk the mashed sweet potato, eggs, and buttermilk until smooth, then whisk in the cooled melted butter.
Pour the wet into the dry and fold with a spatula in about twelve strokes. Stop while the batter still looks slightly rough and streaky.
Fill and Bake
Divide the batter between the twelve cases, filling each about three quarters full, and sprinkle the reserved parmesan over the tops.
Bake 22 to 25 minutes, until a skewer comes out clean and the cheese caps are browned and crisp at the edges. The muffins themselves stay pale, which is correct.
Cool in the tin 5 minutes, then move to a wire rack.
Notes
Roast, do not boil: boiled sweet potato is waterlogged and a sugarless batter cannot hold that water, so you get a gummy streak.
Pale is done: with no sugar there is nothing to brown the batter. Use a skewer, not color, and take them out when it comes back clean.
Grate your own parmesan: pre grated cheese is coated to stop clumping and will not melt into the crumb.
Twelve strokes: sugar tenderizes gluten, so a savory batter toughens faster when overmixed.
Storage: 3 days at room temperature, 5 refrigerated, 3 months frozen. Reheat at 325F for 12 minutes from frozen so the cap crisps again.