Biscuits and Sausage Gravy

Method

1. Heat the oven to 450°F with a rack in the upper third. Whisk 3 cups flour, baking powder, baking soda and salt together in a wide bowl.
2. Grate the frozen butter on the large holes of a box grater directly into the flour, tossing every few strokes so the shreds stay separate and coated. Frozen butter shredded this way melts into steam pockets in the oven, which is what makes the layers.
3. Pour in the cold buttermilk and stir with a fork just until a shaggy, barely cohesive dough forms. There should still be dry crumbs in the bowl — they will get picked up during folding.
4. Turn the dough onto a floured counter and pat it into a 1-inch-thick rectangle. Fold it in thirds like a letter, rotate 90 degrees, pat out and fold again. Do this 4 times total, then pat to a final 1-inch thickness.
5. Cut with a floured 2.5-inch cutter, pressing straight down and lifting straight up. Twisting seals the cut edges shut and the biscuit will bake up lopsided and squat. Press scraps together gently for the last few.
6. Arrange the biscuits on a parchment-lined sheet so the sides just touch — they brace each other and climb higher. Brush the tops with buttermilk and bake 14 to 16 minutes, until the tops are deep gold and the sides look dry and flaky.
7. While the biscuits bake, crumble the sausage into a cold 12-inch skillet and set it over medium. Cook 8 to 10 minutes, breaking it into rough half-inch pieces, until well browned with crisp edges and about 3 tablespoons of fat rendered out. Do not drain the fat — it is the roux.
8. Sprinkle the 1/4 cup flour over the sausage and stir constantly for 90 seconds, until the raw flour smell is gone and the mixture looks like wet sand clinging to the meat.
9. Pour in the warm milk in three additions, whisking smooth after each before adding more. Adding it all at once guarantees lumps.
10. Simmer gently 6 to 8 minutes, stirring often and scraping the pan bottom, until the gravy coats the back of a spoon and a finger drawn through leaves a clean track. Stir in the pepper and nutmeg, then taste and salt hard — country gravy needs more salt than you think. Split the biscuits and ladle the gravy over.