Shortbread:

Mix and rub the butter into the flour to form a crumb-like mixture.

Press this mixture into an oven tray and bake at 160C / 320F  for 40 minutes different ovens will vary.

Caramel Layer:

Melt butter and brown sugar.

Add the condensed milk and bring it to boil until the color becomes slightly darker and thicker.

Now add vanilla essence and mix through.

Once thickened pour the caramel layer over the baked and cooled off base.

Top Layer:

Melt and mix the dark chocolate, butter, and oil in a microwave dish.

Be careful not to burn the chocolate.

Gently pour the melted chocolate over the caramel middle layer.

Decoration:

Carefully melt the milk chocolate in a microwave dish.

Scoop into a disposable piping bag with a tiny opening and drizzle the top with melted white chocolate. It is easier to drizzle this way.

Cover dish with Saran Wrap, a thin, clingy plastic wrap, and chill the millionaire's shortbread for 20 min in the freezer.

Then remove and cut it into squares.

You can store in an airtight container up to a week.