Preheat your oven to 180°C.
Line the baking tin with parchment paper.
Make sure it covers all sides.
This prevents sticking later on.
Beat butter and sugar until light.
This takes about 3 minutes.
Add eggs one at a time.
Beat well after each egg.
Fold in flour and baking powder gently.
Add milk and mix until smooth.
The batter should be creamy.
Pour batter into prepared tin.
Spread it evenly with a spoon.
Bake for 35-40 minutes.
It should be golden on top.
A skewer should come out clean.
Let it cool in the tin.
Put sugar in a saucepan.
Heat on medium until it melts.
Don't stir, just swirl the pan.
It will turn golden brown.
Add butter carefully, it will bubble.
Stir in cream slowly.
Add sea salt and mix well.
Let it cool for 10 minutes.
Pour caramel over cooled traybake.
Spread it evenly to all corners.
Let it set for 30 minutes.
Cut into 16 squares.
Serve and enjoy immediately.