This is a quick and easy not-too-sweet cookie, shaped by rolling into balls rather than rolled out and cut. The dough will keep in freezer for up to a week. The baked cookies will keep in an airtight container for up to 5 days.
Line two large baking sheets with parchment paper.
Whisk together flour, baking powder and salt; set aside.
With mixer, beat butter, 1 cup granulated sugar and brown sugar at medium speed until light and fluffy, about 3 minutes.
Add egg and vanilla; beat at medium speed until combined, about 30 seconds.
Add dry ingredients and beat at low speed until just combined, about 30 seconds.
Place 1/2 cup sugar in shallow bowl.
Roll dough into 1 1/2-inch balls, roll in sugar and place about 2 inches apart on baking sheet. (If the dough seems too sticky to handle, ill a medium-sized bowl half way with cold tap water. Before you roll each ball of dough, dip your hands in cold water and dry--this will keep dough cool and help keep it from sticking to your hands.).
Butter bottom of glass and then dip in sugar.
Flatten dough balls with glass until about 3/4 inch thick.
Bake until cookies are golden brown around edges and very lightly colored, 12 to 15 minutes.
Cool cookies on baking sheets about 3 minutes and then transfer to wire rack and cool to room temperature.