Apple Muffins

Preheat the oven to 180°C (350°F) and prepare the crumble topping.

For the crumble, mix the flour and sugar in a bowl, add the cold butter, and quickly rub it in with your fingers. Chill in the refrigerator.

Dice the apple, lightly dust with flour, and toss gently.

Sift the flour, baking powder, and salt into a bowl.

In another bowl, whisk the egg with the sugar, sour cream, milk, and vegetable oil. Mix very well.

Fold the flour mixture into the wet ingredients, stirring well until no dry lumps remain.

Fold the apples into the batter with a spatula, just until combined.

Spoon the batter into muffin cups, filling them 2/3 full. Top with the chilled crumble and bake in the preheated oven for 25-30 minutes.

Check for doneness with a skewer.