Melt butter in saucepan, remove from heat and mix through chocolate and sugar. Whisk in 2 of the eggs, flour and vanilla. In a separate bowl, beat the crappers out of cream cheese, egg, icing sugar and lemon juice. In a square cake tin pour in ¾ of the brownie batter. Top with cream cheese mix, then blob on remaining brownie mix and swirl through. Bake at 180 deg cel until the middle is just firm.