Add the rice to a medium mixing bowl and rinse the rice with cold water, swirling with your fingers to release the starch. Drain and continue this process a few times, until the water runs clear when it’s drained. Once the water runs clear, let the rice soak for 30 minutes to 1 hour. Drain and set aside.
Fill a large pot with water and bring to a boil over high heat. Spoon two tablespoons of the boiling water into a small bowl. Stir the saffron into the small bowl of water and let sit for at least 10 minutes.
Add salt to the large pot of boiling water, then add the rice and boil until the rice is just tender. Cook until the rice is soft on the outside but still al dente, about 5 to 7 minutes. Drain the rice in a fine mesh sieve and rinse with cold water to stop the rice from cooking. Drain and add to a large mixing bowl.
In a medium mixing bowl stir together the yogurt, saffron water and 4 tablespoons of the melted butter. Stir in 1 heaping cup of the boiled rice.
Heat a 12-inch nonstick skillet over medium heat, add the canola oil and heat through then add the remaining melted butter. Add the yogurt-rice mixture and spread out in an even layer using a wooden spoon.
Pile the remaining rice into the pan, mounding it in a pyramid towards the center. Use the handle of the wooden spoon to make 6 holes in the rice down to the bottom of the pot to allow steam to escape from the bottom and crisp the bottom. The oil and butter mixture should be bubbling up the sides of the pan, add additional oil if needed.
Cook the rice over medium-high heat until the mixture is evenly browned along the edges, about 8 minutes. Cover the mixture with a lid wrapped in a kitchen towel and lower the heat to medium-low. Steam the rice until it’s tender and cooked through, turning the pan every 10 minutes to ensure even browning, about 20 minutes total.
Remove from heat and let cool for 5 minutes then place a plate on top of the pan and invert the rice onto it so the tahdig is on top. Top with the pumpkin seeds and raisins.