Heat oven to 375°F. Beat butter in medium-size bowl until creamy. Beat in egg. Add sugar, flour, salt, and vanilla; on low speed, beat until well blended.Advertisement
Put dough into cookie press fitted with 1-inch sawtooth ribbon disk. Press into long strips on ungreased baking sheets. With floured knife, score strips every 1 inch.
Bake in 375°F oven 6 minutes, until just browning around edges. Cut cookies along score lines; cool on rack.
Melt chocolate in small cup over simmering water, or microwave on high 2 minutes; stir until smooth. Spread 1/2 teaspoon melted chocolate on underside of cookie; top with another cookie, flat sides together. Repeat with remaining cookies. Refrigerate 5 minutes to set. Place nonpareils in dish. Dip 1/2 inch of end of cookie in remaining minutes to set. Place nonpareils in dish. Dip 1/2 inch of end of cookie in remaining chocolate, then in nonpareils. Place on waxed paper; refrigerate to set.