FOR THE STREUSEL
18 whole cardamom pods
2 3/4 cups all-purpose flour
1 cup packed light-brown sugar
1/2 teaspoon salt
1 cup (2 sticks) unsalted butter, softened
FOR THE CAKE
Vegetable-oil cooking spray
2 1/2 cups all-purpose flour
1 teaspoon baking powder
1/2 teaspoon baking soda
2 teaspoons ground cinnamon
1/2 teaspoon salt
3/4 cups (11/2 sticks) unsalted butter, softened
1 1/4 cups sugar
3 large eggs
1 1/4 cups low-fat plain yogurt
1 teaspoon pure vanilla extract
Preheat oven to 350 degrees. Bake cardamom pods on a rimmed baking sheet until fragrant, about 10 minutes. Transfer sheet to a wire rack let cool completely. Finely grind cardamom in a spice grinder. Pass through a large-mesh sieve set aside.
Make the streusel: Whisk flour, brown sugar, 3/4 teaspoon ground cardamom, and the salt in a medium bowl. Cut in butter with a pastry blender until mixture resembles coarse crumbs; set aside.
Coat a 10-inch nonstick angel-foodcake pan with cooking spray set aside.
Make the cake: Sift flour, baking powder, baking soda, 3/4 teaspoon ground cardamom, the cinnamon, and salt into a medium bowl. Put butter and sugar into the bowl of an electric mixer fitted with the paddle attachment; mix on medium-high speed until pale and fluffy. Reduce speed to medium. Mix in eggs, 1 at a time. Reduce speed to low. Add flour mixture in 2 batches, alternating with the yogurt. Mix in vanilla.
Spoon half of the batter into prepared pan. Sprinkle with 2 1/2 cups streusel. Top with remaining batter. Squeeze remaining streusel into large and small clumps; sprinkle on top of batter. Bake until golden brown and a cake tester inserted into center comes out clean, 50 to 60 minutes. Transfer to a wire rack let cool 10 to 15 minutes. Remove cake from pan by slightly raising removable center piece invert onto baking sheet, and then reinvert onto wire rack to cool completely.