In a large bowl, beat butter, sugar and peanut butter until creamy. Add egg and vanilla; beat well. Stir together flour, baking soda and salt; blend into butter mixture. Stir in peanut butter chips; drop by scant 1/4 cupfuls onto ungreased cookie sheet, 6 cookies per sheet
Bake 12 to 16 minutes or until lightly browned around edges. Cool 1 minute; remove from cookie sheet to wire rack. Cool completely.
I definitely keep my eye on these, as soon as I see a slight browning on the edges I take them out of the oven.