Preheat oven to 350°F (175°C). Grease a 6-cup muffin tin.
In a bowl, mix apples with white sugar, 1/8 tsp cinnamon, and 1 tbsp brown sugar. Set aside.
In another bowl, combine flour, oats, 2 tbsp brown sugar, 1/4 tsp cinnamon, and nutmeg. Cut in butter until mixture is crumbly.
Press about 1 tablespoon of the crumble mixture into the bottom of each muffin cup to form a crust.
Divide the apple mixture evenly among the cups.
Top with remaining crumble mixture, pressing gently.
Bake for 20–25 minutes, or until golden and bubbly.
Let cool slightly before removing. Serve warm or at room temperature.