Banana Black Walnut Oatmeal Scones

1½ cups old-fashioned rolled oats or quick oats
1½ cups unbleached all-purpose flour
⅓ cup sugar, plus 1 tablespoon for sprinkling
2 teaspoons baking powder
½ teaspoon salt
10 tablespoons cold unsalted butter, cut into ½ʺ cubes
¾ cup black walnut pieces
¼ cup whole milk
¼ cup heavy cream
1 large egg
½ teaspoon imitation banana extract
1 very ripe frozen banana, peeled

Heat oven to 375°, and adjust oven rack to the middle position. Spread oats evenly on a baking sheet, and toast in the oven until fragrant and lightly browned, 7-9 minutes. Cool on a wire rack. Increase the oven temperature to 425°.

In a food processor, pulse flour, sugar, baking powder and salt until combined, about four 1-second pulses. Scatter cold butter evenly over dry ingredients, and pulse until the mixture resembles coarse cornmeal, about 12 1-second pulses. Transfer mixture to a medium bowl; stir in walnuts and cooled oats.

Add milk, cream, egg, banana extract and banana to the food processor. Reserve ¼ cup of the mixture for glazing. Add cream mixture to the oat mixture. Mix the dough by hand in the bowl until the dough forms a cohesive mass.

On a parchment paper-covered work surface, turn the dough out. Gently pat into a 7ʺ circle about 1ʺ thick. Using a pie separator or chef’s knife, cut the dough into eight wedges and set on a parchment-lined baking sheet, spacing them about 2ʺ apart. Brush surfaces with the reserved cream mixture, and sprinkle with 1 tablespoon sugar.

Bake until golden brown, 12-14 minutes. Leave the scones on the baking sheet and cool on a wire rack for 5 minutes, then remove the scones from the pan to the cooling rack for about 30 minutes before serving.