Line a loaf tin (25cm x 11cm) with baking paper.
Peel the apples, remove the core and cut into pieces.
Mix the brown sugar and cinnamon in a small bowl and set aside.
Beat the softened butter, sugar and vanilla extract until light and fluffy.
Beat in the eggs one by one.
Mix flour with baking powder.
Stir the flour and milk into the butter mixture.
Pour half of the batter into the loaf tin and smooth out.
Top with half of the apples and sprinkle with half of the cinnamon sugar.
Press down a little.
Pour the remaining batter over the top and smooth it down.
Top with the remaining apples.
Sprinkle with the remaining cinnamon sugar.
Bake in preheated oven at 180° C for about 60 minutes.