In a medium bowl, cream together the butter and sugar until light and fluffy. Beat in the eggs and vanilla. Combine the flour, baking powder, and salt; stir into the creamed mixture. Cover, and chill dough for at least one hour.
Roll the dough into 1 inch balls, and place onto ungreased cookie sheets. Make an indentation in the center of each cookie with your thumb.
Bake for 8 to 10 minutes in the preheated oven, or until lightly golden. Immediately make indentations into them again with the handle of a wooden spoon. Fill each indentation with white chocolate chips.
Allow cookies to cool on baking sheet for 5 minutes before transferring to a wire rack to cool completely.
Interesting Facts
White chocolate chips are made from cocoa butter, milk solids, and sugar.
These cookies can be stored in an airtight container for up to two weeks.
You can use different types of chocolate chips in the cookies, such as dark or semi-sweet, for a different flavor.