Preheat the oven to 425 degrees. Melt ½ cup of butter in a deep 9x9 baking dish.
In a large bowl, combine all the dry ingredients for the biscuits. Create a well in the middle and add the buttermilk. Mix until the batter resembles cake batter. Pour the batter into the melted butter and spread it out.
Bake for 25-30 minutes. Check halfway to ensure the tops are not getting too brown. If needed, cover with foil. Insert a toothpick into the middle, and when it comes out clean, the biscuits are done.
Brown the sausage with 1 Tbsp of vegetable oil. Once browned, add all the seasonings, followed by flour. Cook for 1 minute. Slowly pour in milk, ½ cup at a time, until the gravy thickens.
Cut the biscuits into squares and top with hot sausage gravy.