Preheat oven to 425 degrees. Line a 13 x 18-inch pan with a silicone liner (or use non stick cooking spray).
Melt butter, set aside to cool.
Whisk together flour, oatmeal, sugar, baking powder and salt in a large bowl.
In a small bowl, combine milk, egg and vanilla extract; blend well. Add the melted and cooled butter, stir till butter clumps up.
Add to dry ingredients all at once; stir with a wooden spoon just until dry ingredients are moistened.
In another small bowl, combine the 2 Tablespoons sugar with the cinnamon; mix well. Sprinkle evenly over dough in bowl; gently stir in just to get swirls in the dough. (Do not blend completely).
Use an ice cream scoop or 1/4 cup measuring cup to drop mounds of dough 2 inches apart on cookie sheet.
Bake at 425° for 11-13 minutes or until golden brown. Cool 5 minutes.
Whisk together glaze ingredients, adding enough milk to get a thin consistency. Drizzle glaze over scones. Serve warm.