1. Place chopped pecans in a single layer in a shallow pan.
2. Bake at 350° for 7 minutes or until pecans are lightly toasted, stirring occasionally.
3. Beat egg whites, cream of tartar, and salt at medium speed with a heavy-duty electric stand mixer until frothy; increase speed to high, and gradually add brown sugar, beating until stiff peaks form. Gently fold in toasted chopped pecans.
4. Drop batter by heaping teaspoonfuls 1 inch apart onto lightly greased aluminum foil-lined baking sheets. Press 1 pecan half into each cookie, flattening slightly.
5. Bake at 325° for 33 minutes or until pecan halves are toasted and cookies are lightly golden. Let cool on baking sheet 1 minute. Transfer to wire racks; let cool 20 minutes. (Cookies will crisp while cooling.) Store in airtight containers up to 1 week.