Step 1

Heat the oven to 400°F with a rack in the middle position. Line a rimmed baking sheet with kitchen parchment. In a large bowl, toss the oats with ¼ cup maple syrup until evenly coated. Distribute in an even layer on the baking sheet; reserve the bowl. Bake until golden brown, 7 to 8 minutes, stirring once halfway through. Cool on a wire rack for 10 minutes, then transfer to a small bowl; reserve the baking sheet and parchment. Increase the oven to 450°F.

Step 2

In a small bowl or 2-cup liquid measuring cup, whisk together the buttermilk, egg and the ¼ cup remaining maple syrup; set aside. In a food processor, combine ½ cup of the toasted oats, the flour, white sugar, baking powder, baking soda, salt and nutmeg. Process until the oats are as fine as the flour, about 15 seconds.

Step 3

Scatter the butter over the flour mixture, then pulse until the pieces are no larger than about ¼ inch, about 15 pulses. Transfer to the reserved bowl. Add ¾ cup of the remaining toasted oats to the flour-butter mixture; toss. Pour in the buttermilk mixture, then fold with a silicone spatula just until a shaggy dough forms; it’s OK if some dry pockets remain.

Step 4

Lightly dust the counter with flour, then turn the dough out onto it. Using your hands and working quickly, gently knead the dough just until cohesive, about 5 turns; do not overwork the dough. Gather the dough and press it into a 6-inch disk about 1½ inches thick. Using a chef's knife, cut the disk in half, then cut each half into 4 wedges. Place the wedges on the reserved baking sheet, spaced evenly apart; refrigerate uncovered for at least 15 minutes or up to 1 hour.

Step 5

Bake the scones until golden brown, 13 to 15 minutes. Cool on the baking sheet on a wire rack for 5 minutes. Transfer directly to the rack and cool for another 5 minutes; reserve the baking sheet.

Step 6

To make the glaze, in a medium bowl, whisk the melted butter, powdered sugar, maple syrup, buttermilk and nutmeg until smooth. The glaze should have the consistency of pourable yogurt; if it’s too thick, thin it by stirring in additional buttermilk 1 teaspoon at a time. Set the rack with the scones in the reserved baking sheet. Using a spoon, drizzle the glaze onto the scones (it’s fine if they’re still slightly warm), then sprinkle with the remaining toasted oats. Let the glaze dry for at least 10 minutes.