Prepare a 9x9" baking pan by either greasing with butter or line with parchment paper.
In a small bowl, melt white chocolate with ¼ cup butter just till smooth. Cool slightly.
In a medium bowl, mix together sugar, ¼ cup butter and vanilla with a mixer till fluffy.
Add melted chocolate to the sugar mixture and blend. Add eggs one at a time and mix.
In a small bowl, combine flour, salt, baking powder and baking soda. Add to chocolate mixture and blend only till combined.
Fold in chocolate chips. Turn into baking pan and bake for 30 minutes.