Preheat oven to 375°F (190°C). Line a baking sheet with parchment paper.

In a large bowl, whisk together flour, oats, brown sugar, baking powder, and 2 teaspoons (6 grams) salt. Using a pastry blender or 2 forks, cut in cold butter until mixture resembles coarse crumbs.

In a small bowl, stir together 1 cup (240 grams) cold buttermilk and maple extract. Gradually add buttermilk mixture to flour mixture, stirring with a fork just until dry ingredients are moistened.

Turn out dough onto a clean surface; gently knead until dough comes together, 8 to 10 times. On a very lightly floured surface, roll dough into a 7-inch circle (about 1 inch thick). Using a 2½-inch round cutter dipped in flour, cut dough without twisting cutter, rerolling scraps as necessary. Place 2 inches apart on prepared pan. Freeze for 15 minutes.

Bake until lightly golden and a wooden pick inserted in center comes out clean, 15 to 20 minutes. Let cool on pan for 5 minutes.

In a small bowl, whisk together confectioners’ sugar, maple syrup, remaining 3 tablespoons (45 grams) buttermilk, and remaining ½ teaspoon (1.5 grams) salt until smooth. Just before serving, dip top of scones in glaze. Garnish with toasted oats, if desired. Store in an airtight container for up to 4 days.