For the Biscuits:

1. Preheat the oven: Set your oven to 425°F (220°C). Line a baking sheet with parchment paper.
2. Mix dry ingredients: In a large bowl, whisk together the flour, baking powder, baking soda, and salt.
3. Cut in the butter: Add the cold butter cubes to the dry mixture. Use a pastry cutter or your fingers to blend until the mixture resembles coarse crumbs.
4. Add the buttermilk: Gradually pour in the buttermilk and stir until the dough comes together. If it feels too dry, add a splash more buttermilk.
5. Shape and cut: Turn the dough out onto a floured surface and gently knead it 3–4 times. Pat it into a 1-inch thick circle and cut out biscuits using a round cutter or glass. Gather and reshape scraps as needed.
6. Bake: Place the biscuits on the prepared baking sheet and bake for 12–15 minutes, or until golden brown on top. Remove and let cool slightly.

For the Gravy:

1. Cook the sausage: In a large skillet over medium heat, crumble and cook the sausage until browned and fully cooked. Remove the sausage with a slotted spoon, leaving the grease in the skillet.
2. Make a roux: Sprinkle the flour over the grease and whisk continuously for 1–2 minutes until lightly golden. This helps thicken the gravy.
3. Add milk gradually: Slowly pour in the milk, whisking constantly to prevent lumps.
4. Season: Stir in the cooked sausage, black pepper, and salt. Let the gravy simmer for 5–7 minutes, stirring occasionally, until it thickens to your desired consistency. If you like it thinner, add a splash more milk.
5. Taste and adjust: Adjust the seasoning by adding more salt, pepper, or red pepper flakes, if desired.

To Serve:

1. Split the warm biscuits in half and place them on a plate.
2. Generously ladle the hot sausage gravy over the biscuits.
3. Garnish with fresh herbs like parsley (optional) and serve immediately.