In a large bowl using an electric mixer beat together sugar, eggs and orange zest until light, creamy and triple in volume, approximately 3-4 minutes. Lower speed and slowly add butter to incorporate. Continue adding yogurt, Grand Marnier and cardamom. Add half the sifted flour mixture and half the orange juice, beating until combined. Add remaining flour and orange juice beating until smooth, approximately 30 seconds. Pour into prepared pan and smooth out top. Bake for 37-40 minutes or when a toothpick inserted into center comes out clean.