sweet potato (and marshmallow) biscuits

INGREDIENTS

• 1 pound sweet potatoes (red skinned are my favorite)
• 1/3 cup (79 ml) buttermilk
• 2 cups (250 grams) all-purpose flour
• 1 tablespoon (15 grams) baking powder
• 3 tablespoons (38 grams) granulated sugar
• 1 teaspoon ground (2 grams) cinnamon
• 1/4 teaspoon ground nutmeg
• 1/4 teaspoon ground ginger
• 1/8 teaspoon ground cloves
• 1/2 teaspoon (2 grams) table salt
• 5 tablespoons (71 grams) unsalted butter, cold
• 1 cup miniature marshmallows (optional)