Adjust oven rack to middle position; heat oven to 375-degrees.
Spread oats evenly on baking sheet and toast in oven until fragrant and lightly browned, 7-9 minutes. Cool on wire rack; reserve 2 TB for surface work.
Increase oven temp to 425-degrees.
Spray second baking sheet with non-stick spray and line with parchment paper.
Whisk wet ingredients (half & half, egg, and vanilla) in large measuring cup until incorporated; reserve 1 TB for glazing.
In food processor, pulse dry ingredients (excluding butter) until combined, about four 1-second pulses
Scatter cold butter evenly over dry ingredients and pulse until mixture resembles coarse cornmeal, twelve to fourteen 1-second pulses.
Add cooled oats and addin ingredients to processor and pulse two more times.
Transfer mixture to medium bowl. Using rubber spatula, fold in liquid ingredients until large clumps form. Mix dough in bowl until dough forms cohesive mass.
Dust work surface with half of reserved oats, divide dough into two equal portions and turn out onto work surface, and dust top with remaining oats.
Gently pat each portion into separate 5-inch circles about 1-inch thick. Using bench scraper or chef's knife, cut dough from each circle into 8 wedges and set on parchment-lined baking sheet, spacing about 1 inch apart.
Brush surfaces with reserved egg mixture and sprinkle with 1 TB sugar.
Bake until golden brown, 12 to 14 minutes.
Cool on baking sheet for 5 minutes then remove scones to cooling rack and cool to room temperature, about 30 minutes. Serve