1 cup sugar
1.5 cups water
1 orange, sliced
1-1/2 cups all purpose flour
1 tsp baking powder
1/2 tsp baking soda
1/2 cup vegetable oil
1 tsp vanilla extract
1/2 cup powdered sugar
1/2 cup yogurt
1/4 cup fresh orange juice
2 tbsp orange zest
2 tbsp walnuts, chopped