01 - Line an 8x4 inch loaf pan with parchment paper, allowing overhang on opposite sides for easy removal.
02 - Combine sugar and water in a medium saucepan. Heat over medium heat, stirring until sugar dissolves. Bring to a gentle boil and cook without stirring until thermometer reaches 245°F (soft ball stage).
03 - While syrup cooks, whisk tahini, matcha powder, and salt in a mixing bowl until completely smooth and uniform.
04 - Immediately pour hot syrup into tahini mixture. Stir vigorously with a wooden spoon for 20-30 seconds until mixture thickens, appears matte, and begins pulling away from bowl sides.
05 - Quickly scrape mixture into prepared pan. Smooth top evenly with spatula or back of spoon.
06 - Let cool at room temperature for 10 minutes. Refrigerate for at least 1 hour until firm and set completely.
07 - Lift halva from pan using parchment overhang. Cut into 12 equal squares. Serve at room temperature for best texture.