Preheat the oven to 350 F.Put flour, baking powder and salt in a small bowl. Set aside.In a large bowl, add the sugar and eggs and whisk until combined. Add the orange zest, vanilla extract and buttermilk and whisk until combined. Add the cooled melted butter and whisk to combine. Add the flour and carefully whisk until just combined, being careful not to over-whisk.Pour into a buttered and floured loaf pan. Bake for 30 minutes. Cool on wire rack
Glaze
Combine ingredients in a small pot. Heat until everything is incorporated. Pour on top of cake.
Candied Oranges
Slice fruit into 1/4 inch slices. In a wide pot, heat and stir water and sugar until the sugar dissolves. Bring to a gentle boil and add the orange slices. After 15 minutes, lower the heat to medium-low. Flip over the slices and continue cooking on low for another 15-20 minutes, until the peel becomes translucent and the syrup has thickened. Place a wire rack on top of a lined baking sheet, and transfer the candied slices on top to cool.