Pre-heat oven to 350 F degrees F. Grease an 8.5" by 4.5" loaf pan with baking spray with flour.
In a small mixing bowl combine the flour, baking powder, and salt, whisking gently to combine. In another, medium-sized mixing bowl whisk the butter, sugar, and rose water until pale and creamy, about 1 minute. Next, whisk in the egg until smooth.
Alternately add the flour and milk to the butter mixture until just combined- Do not over mix. Pour the batter into the prepared pan. Bake for 35 minutes until golden brown and a toothpick comes out clean.
Cool for 10 minutes in pan on rack. Then remove from pan to cool on a wire rack.
Use a pastry brush to coat the top of the cake with melted butter, then sprinkle with the powdered sugar. Serve immediately or enjoy at room temperature for a week!