Preheat your oven to 160°C fan.
Grease your cake tin thoroughly with butter.
Line the base with baking parchment.
This prevents sticking later on.
Cream butter and sugar until light and fluffy.
Beat in eggs one at a time.
Add vanilla extract and mix well.
Fold in the flour gently using a spoon.
Peel and chop apples into small pieces.
Stir apples and sultanas into the batter.
Add cinnamon and milk to loosen the mixture.
Mix everything together until just combined.
Pour batter into your prepared tin.
Smooth the top with a spatula.
Bake for 55-65 minutes until golden.
A skewer should come out clean when done.
Let the cake cool in the tin.
Transfer to a wire rack after 10 minutes.
Slice and serve when completely cooled.