Step 1: In a non-stick frying pan, fry the sesame seeds on medium low heat for about 10 minutes, until fragrant and pan begins to smoke. Remove and cool completely.
Step 2: Drain the rice and blend with enough water until mixture is smooth. Remove and clean blender.
Step 3: Repeat this process with the black sesame seeds until mixture is a grayish paste and free from lumps.
Step 4: In a large pot, add the grinded ingredients, pandan leaves and sugar.
Step 5: Stir to mix and bring to a boil on high heat. Lower heat to medium, stirring the mixture until it thickens slightly.
Step 6: Add in sugar and butter to mixture and more water if mixture get to thick.
Step 7: Simmer for another 15 minutes until mixture is smooth, season to taste with sugar if needed.
Step 8: Remove pandan leaves before serving.