Spread the sesame seeds on a pan and toast in preheated oven at 180ºC for 5 minutes. Bring honey to a boil. Add seeds and continue cooking on medium heat to 140ºC (light crack reading). Watch it carefully, it burns quickly. Pour into buttered pan, and flatten with spatula to 1 cm thickness. Score into 5 cm pieces while hot. Allow to cool. Store in plastic bag.