Heat oven to 425°F (220°C). Line a baking sheet. Whisk 300 g flour, baking powder, and 1/2 teaspoon salt. Cut in cold butter until pea-sized pieces remain.

Stir in buttermilk just until a shaggy dough forms. Pat onto a floured surface, fold over itself three times, and pat 1 inch thick. Cut 6 large biscuits, gently gathering scraps if needed.

Bake 15 to 18 minutes until risen and golden. While they bake, brown sausage in a large skillet over medium heat for 8 to 10 minutes, breaking it up, until it reaches 160°F (71°C).

Keep about 2 tablespoons rendered fat in the skillet with the sausage, draining excess. Stir in 30 g flour; cook 1 minute. Gradually stir in milk, scraping the bottom.

Simmer gently 4 to 6 minutes, stirring, until thick enough to coat a spoon. Add pepper and salt to taste. Split each biscuit and serve with one-sixth of the gravy.