Stir together 2 cups pecan halves, 1/2 cup firmly packed light brown sugar, and 6 Tbsp. dark corn syrup in a small bowl. Spread mixture in a lightly greased aluminum foil-lined jelly-roll pan. Bake at 350° for 12 to 15 minutes or until glaze thickens, stirring every 4 minutes. Spread in a single layer on wax paper; cool completely, separating pecans as they cool. (For the prettiest garnish, leave some in clusters.) Store in an airtight container at room temperature.