Get a large freezer bag that will be able to accommodate all the drumsticks in. Freezer bag is better as the chicken will marinade more "evenly". Add in the rest of the ingredients. Push the air out and seal the bag. Squish it around so they are marinated evenly.
The next day:
Preheat oven to 425 F. Line your roasting pan with aluminum foil. Take the drumstick pieces out from the freezer bag (keep the marinating juice) and shake off any excess and arrange on the roasting pan. Brush each drumstick with some oil and pop them into the oven and bake until they are golden brown. It may take somewhere around 30-45 minutes depending on your oven.
In a medium sauce pan, melt about 1 Tbsp of butter, add in the mushrooms (if using, if not using you can go ahead and skip this part) and stir-fry until they are soft, remove from the pan and set aside. Melt another 2 Tbsp of butter, add in the all purpose flour and cook them over medium heat until they turn slightly brownish. Gradually add in the buttermilk juice from marinating the chicken and stir constantly until they are thickened, add the mushrooms back into the pan, have a taste and add more salt if needed. Serve with the chicken on the side and sprinkle some paprika powder over the creamy sauce if you desire