1 1/4 cups peanut butter, smooth or chunky (divided)
1/4 cup unsalted butter (1/2 stick softened)
1/2 cup (packed) dark brown sugar
1/2 cup granulated (white) sugar
1 large egg
1/2 teaspoon pure vanilla extract
3/4 cup unbleached all-purpose flour
1/2 cup whole wheat pastry flour
1/2 teaspoon baking powder
1/2 teaspoon baking soda
1/2 teaspoon salt
1 pint vanilla or chocolate ice cream (softened slightly)