Preheat the oven to 350 degrees.
Cream the butter and sugar until smooth.
Add the eggs and vanilla and again beat until smooth.
Add the flour, baking soda, baking powder, and salt and beat on low until the flour is mixed in and then beat on medium until dough is thoroughly mixed together.
Add the white chocolate chips and beat once again until chips are mixed evenly.
Turn the sugar cookie dough into a greased 9x13. Wetten your fingers and press the dough evenly into the pan. Re-wetten your fingers if the dough starts to stick so you can pat the dough down evenly.
Bake for 21 minutes. They should be slightly golden brown but mostly if you touch them you'll think they are too soft to be done. This is the key to making these bars spectacular! Set aside to cool.