Peanut Butter Sandwich Cookies

Cookies: Heat oven to 350 degrees F. Line 2 baking sheets with parchment paper. In a medium bowl, whisk together flour, baking soda, baking powder, and salt. In a large bowl, beat butter and sugars until well blended, then add peanut butter. Add egg and vanilla. Beat in flour mixture until just blended. Stir in peanut butter chips. Drop 8 2-tablespoon balls of dough on a prepared baking sheet, about 3 inches apart. Press a floured fork into each to make a crosshatch design and to spread dough to 3-inch rounds. Bake about 12 minutes, or until cookies are browned around the edges. Let stand 2 minutes on baking sheet, then remove to a wire rack to cool completely. Repeat with remaining dough on second sheet. Filling: In a microwave-safe bowl, melt chocolate and butter for 1 minute. Whisk until smooth, then stir in vanilla. Chill until filling is thick enough to spread. Spread filling on the bottom of one cookie, then press another on top to make a sandwich. Repeat with remaining cookies.