Preheat oven to 300F. Line a baking sheet with parchment paper.
Beat egg whites, cream of tartar and salt with a mixer at high speed until soft peaks form. Add sugar, 1 tablespoon at a time, beating until stiff peaks form. Sift cocoa and espresso powder over egg white mixture; fold in. Fold in minichips.
Drop batter by level tablespoonfuls onto prepared pan; alternately fill a disposable pastry bag with batter and pipe a small amount (about 1 tablespoon of batter for each meringue) onto pan. Bake 40 minutes, or until crisp. Cool on pan on a wire rack. Repeat procedure with remaining batter, reusing parchment paper. Store in an airtight container.