Apple walnut crumb cake - Moje wypieki

Ingredients

• 150 g butter
• 140 g caster sugar
• 3 large eggs
• 1 tsp vanilla extract
• 125 g soured cream
• 220 g plain flour
• 1 and 1/4 tsp baking powder
• 3 – 4 medium-sized apples
• 75 g plain flour
• 75 g walnuts or pecans, chopped
• 1/2 cup light brown sugar
• a pinch of salt
• 60 g butter, melted