Preheat your oven to 425℉. Prepare a baking sheet lined with parchment paper or a silicone baking mat.

Whisk together the flour, sugar, baking powder, salt, granulated garlic and nutritional yeast in a large mixing bowl. Work in the butter using a pastry cutter until the mixture is a little crumbly. Stir in the chopped scallions and cheese (if you're using cheese instead of the nutritional yeast).

In a small bowl, whisk together the sweet potato purée, 2 tablespoons milk and egg substitute (or two eggs). Add this mixture to the dry ingredients and add the 1/4 cup milk gradually as you stir the mixture together. You may not need to use the entire 1/4 cup milk but I did. This dough may be a little sticky.

Scrape the dough onto a lightly-floured work surface, shape it into a round and flatten with your hand until the dough is roughly 1/2 - 3/4 inch thick. Use a round cookie cutter to cut a piece of dough and transfer to the prepared baking sheet. I used a large cookie cutter (3-inches) so this batch yielded 9 biscuits. Reshape the dough into a disk and cut round pieces with your cookie cutter until all the dough has been used up. You can use a smaller cookie cutter; baking time will be a minute or two shorter.

Brush the tops with a little milk and bake in the oven for 12-15 minutes, depending on biscuit size. Serve warm. These will keep in the refrigerator and are great toasted the next day.