Heat oven to 350°F (177°C).
Mix together the chopped apples, sugar, flour, cinnamon, and vanilla in a small bowl.
Transfer the apples to a 10-ounce ramekin.
In a small bowl, stir together flour, oats, brown sugar, and cinnamon. Cut the softened butter into small pieces and add them to the bowl. Blend in the butter using a fork or your fingers and mix until well combined.
Scatter the topping evenly over the apples. Place the ramekin on a small rimmed baking sheet.
Bake for 30-35 minutes or until apples are soft and the topping is golden.
