Step 1 Heat the oven to 350 degrees. Soak the saffron in 2 tablespoons of very warm water for 20 minutes, then set aside.
Step 2 Mash the dates with a fork, then roll the small mashed pieces into small pea-sized balls (about 2 dozen) and set aside.
Step 3In the bowl of a stand mixer, or in a large bowl with a hand mixer, whisk together the eggs and sugar until light, fluffy and almost meringue-like in texture, 7 to 10 minutes. Gently whisk in the cardamom and turmeric.
Step 4In a small bowl, sift together the flour and baking powder, then slowly add them to the egg mixture while whisking. Continue whisking while you add the saffron-infused water and oil just until combined.
Step 5Grease a round 9-inch springform or regular cake pan with butter and line with parchment paper. Butter the top of the parchment paper. Dust the bottom and sides with 2 teaspoons of the sesame seeds.
Step 6Pour half the cake mixture into the pan, scatter with the tiny date balls, then cover with the remaining mixture and a last sprinkling of sesame seeds. Top with chopped walnuts.
Step 7Bake for 35 minutes, or until the cake is golden brown on top (a toothpick inserted in the middle should come out clean).
Step 8Cool the cake, then release the spring and turn upside down onto a plate. Invert again and serve with a spoonful of creme fraiche or a scoop of vanilla ice cream.