Preheat the oven to 175° traditional heat. Grease a 27x10cm cake tin. Line it with a sheet of baking paper to facilitate unmolding.
In a food processor or hand mixer, beat the softened butter and powdered sugar until the mixture is creamy, 3-4 minutes.
Add the eggs one at a time, mixing between each and scraping the edges.
In a bowl, sift the dry ingredients: flour, salt and baking powder.
In another container, mix the single cream, orange zest, orange juice and vanilla.
Add the dry ingredients alternately with the liquid mixture. Finish with the dry ingredients (mix just enough, without overdoing it).
Pour the batter into the mold and bake for about 1 hour (depending on your oven). Test for doneness with a wooden pick that should come out clean or with a few crumbs.
Leave to cool in the mold for 15 minutes, then unmold on a wire rack. Then let cool completely.
Orange glaze
In a bowl, mix the icing sugar, cream, orange juice and orange zest until smooth. If it's too thick, add orange juice, if it's too runny, add icing sugar.
With a spoon, coat the icing on the cooled cake by making zigzags.
Notes
This orange cake will keep for about 2 days at room temperature (this is what keeps it moist).Otherwise, it can be kept 4-5 days in the refrigerator.