Making the cake

Preheat the oven to 180ºC.

Grease a traybake tin and line with parchment paper.

Fit the K-Beater.

Add butter, sugar and salt into the appliance bowl.

Mix for 4 minutes on speed 3 until light and fluffy.

Add eggs, flour and baking powder.

Mix for 2 minutes on speed 1 until smooth.

Transfer the batter into the tin and level with a spatula.

Bake for 20 minutes at 180ºC until a skewer inserted comes out clean.

Remove from the oven and let cool completely.

Making the topping

Add 100 g milk, cornflour and sugar into a small bowl and mix to combine.

Add the remaining milk into a saucepan.

Heat on a medium-high heat until near boiling. 

Reduce the heat to a low heat.

Add the cornflour mixture.

Cook for 1-2 minutes on a low heat stirring constantly, until the mixture has thickened. 

Transfer the mixture into a clean bowl and cover with plastic wrap.

Let cool slightly, being careful not to let the mixture thicken too much.

Add vanilla extract and sour cream into the topping mixture and mix to combine.

Spread the topping evenly onto the cake and level with a spatula.

Chill in the fridge for 1 hour.

Place apricot halves onto the cake, flat side down.

Chill in the fridge until ready to serve.

Cut into squares.

Serve.