Grind the rice until fine powder, grind the mastic as well.
Add all the ingredients together - except for the ones for serving- and mix well.
Store in an air tight container until you are ready to use.
In a sauce pan over medium heat, add 2 cups of milk to 6 Tbs of the powder you've made, and mix well.
Keep stirring until the mixture gets thick and bubbly.
Pour into serving cups, garnish top with nuts, cinnamon and raisins.
If you want your sahlab a little sweeter you can add more sugar to it while it is cooking on the stove top. If you are used to a super thick sahlab then add more of the powder you've made until you reach your preferable thickness.