Preheat oven to 180°C/350°F.

Grease a 20cm / 8" springform pan with butter, then line with baking paper.

For the apples: Peel and core the apples, slice them, and mix with 2 1/2 tsp cinnamon powder, 50g melted butter, and 2 tbsp white sugar. Set aside.

For the batter: In a bowl, mix 1 1/2 cups flour, 2 tsp baking powder, and 1/2 tsp salt.

In another bowl, combine 4 tbsp melted butter, 1/2 cup oil, 2 large eggs, 3/4 cup sugar, and 2 tsp vanilla extract. Mix until smooth.

Gradually add the dry ingredients to the wet mixture and stir until combined.

Pour half of the batter into the prepared pan.

Arrange half of the apple mixture on top.

Pour the remaining batter over the apples and top with the rest of the apple mixture.

Bake in the preheated oven for about 50-60 minutes or until a toothpick comes out clean.

Mix 1 1/2 tbsp apricot jam with 1 tbsp water in a small saucepan over low heat until smooth.

Brush this glaze over the warm teacake.