Preheat
the oven to 375°F/190°C/gas 5. Set out a 14-inch
(35-cm) pizza pan.
Sift the
flour, baking soda, and salt into a medium bowl.
Beat the butter and granulated and brown sugars
in a large bowl with an electric mixer at high
speed until creamy.
Add the
vanilla and eggs, beating until just blended.
Mix in the dry ingredients and chocolate chips.
Spread the
mixture in the pan. Bake for
20-25
minutes, or
until lightly browned. Cool completely in the
pan. Cut into wedges.