Preheat the oven to 180°C (350°F). Prepare a cupcake pan by greasing it with a little oil or butter and dusting it with a small sprinkle of flour.

In a mixing bowl, combine the oat flour, all-purpose flour, sugar, baking powder, baking soda, and salt until the ingredients are well mixed.

In another bowl, whisk together the egg, oil, milk, and vanilla extract until you get a creamy mixture.

Add the oat flour mixture to the egg mixture, stirring after each addition until you get a smooth, homogeneous cake batter.

Pour the batter into the previously prepared cupcake molds, filling them only one-third full.

Bake the cupcakes in the oven for 20-25 minutes, or until a toothpick inserted into the center comes out clean.

Remove the pan from the oven and let the cupcakes cool before serving.