PLACE oven rack in center position; PREHEAT oven to 450°F.
PROCESS the DRY INGREDIENTS in a food processor until thoroughly combined (1 3/4 cups bread flour, 1/4 cup cornstarch, 1 tablespoon baking powder, 1 1/4 teaspoons salt, 1 1/4 teaspoons granulated sugar, 1/2 teaspoon Butter Buds seasoning, 1/4 teaspoon baking soda, 1/8 teaspoon Accent seasoning, 1/8 teaspoon white pepper).
ADD 1/8 cup vegetable shortening plus 1/8 cup cold solidified coconut oil by tablespoonfuls to the dry ingredients in food processor; PROCESS mixture until fine and crumbly.
WHISK 3/4 cup buttermilk with 1 egg white in a 2-cup pour-spout measuring cup; POUR mixture through the feeder on food processor while running; PROCESS dough until it comes together and blades begin to slow down.
TRANSFER dough mixture onto a generously floured board; ROLL dough very thinly using a rolling pin, using as few passes as possible over dough; RE-FLOUR board (and re-flour whenever needed to prevent dough from sticking); FOLD in half, then into half again; ROLL dough very thinly in the same previous manner; REPEAT rolling and folding no more than 3 times, to insure flakiness without over-working dough; ROLL dough into a rough ball.
ROLL dough with rolling pin until it is between 1/2" - 3/4" thick; CUT into rounds using a biscuit cutter or small drinking glass, re-piecing and re-using scraps.
ARRANGE biscuit dough rounds on a baking sheet.
MELT approximately 2 tablespoons margarine or butter; STIR in 1 pinch salt and 1 pinch granulated sugar; BRUSH tops of each baked biscuit evenly with this BASTE (biscuits may be re-basted after baking if desired).
BAKE biscuits on the center rack at 450°F between 10-13 minutes, or until golden brown (oven temperatures vary, so have oven light on to keep an eye on them).