Preheat the oven to 350°F (175°C). Grease a standard 10-cup bundt pan with butter and dust it lightly with flour.
In a medium bowl, whisk together the flour, 2 teaspoons of ground cardamom, baking powder, baking soda, and salt.
In a large bowl, use an electric mixer on medium speed to beat the butter, granulated sugar, and orange zest until pale and fluffy, about 3 minutes.
Add the eggs one at a time, beating well after each addition. Mix in the vanilla extract.
Reduce the mixer speed to low. Add one-third of the flour mixture, followed by half of the buttermilk and the 1/4 cup (60ml) of orange juice. Repeat, ending with the final third of the flour mixture. Mix just until combined.
Pour the batter into the prepared bundt pan and smooth the top. Bake for 45 to 50 minutes, or until a wooden skewer inserted into the center comes out clean.
Let the cake cool in the pan for 15 minutes before inverting it onto a wire rack to cool completely.
In a small bowl, whisk the powdered sugar, 2 tablespoons of orange juice, and 1/4 teaspoon of cardamom until smooth. Drizzle the glaze over the cooled cake.