Preheat the oven to 400°F. Grease a 9-inch round cake pan with nonstick cooking spray.
In the bowl of a food processor fitted with a metal blade, com- bine the flour, oats, butter, baking powder, baking soda, and salt. Pulse until coarse crumbs are formed. Transfer this mixture to a large bowl.
Add the half-and-half, maple syrup, and vanilla. Stir quickly until a thick batter is formed.
Spoon this mixture into the prepared pan and bake until a tes- ter inserted in the middle comes out clean, about 20 minutes. Cool slightly in the pan on a rack.
Meanwhile, prepare the glaze by combining the confectioners’ sugar, milk, and maple flavoring in a small bowl. Drizzle this glaze over the warm cake and allow to cool completely before serving.