Quick 3-Minute Apple Cake

Ingredients
1/2 small apple, peeled, cored, and finely chopped
4 tbsp all-purpose flour
1/4 tsp baking powder
2 tbsp granulated sugar (adjust to taste)
1/2 tsp ground cinnamon
2 tbsp milk
1 tbsp vegetable oil (or melted butter)
1/4 tsp vanilla extract