2 large orange – finely grated zest only (about 2 tbsp)
1.5 cups granulated sugar
1 cup unsalted butter – softened
4 large large eggs – at room temperature
0.5 cup sour cream – at room temperature
2 tbsp orange juice – freshly squeezed (for batter)
1 tsp vanilla extract
1 cup confectioners' sugar
3 tbsp orange juice – freshly squeezed (for glaze)
Instructions
Preheat the oven to 325°F (165°C). Grease a 9×5-inch loaf pan with the vegetable oil and line it with a parchment sling.
In a medium bowl, whisk together the all-purpose flour, baking powder, and fine salt; set aside.
In a large mixing bowl, combine the granulated sugar and the orange zest. Rub them together with your fingertips until the sugar is fragrant and lightly tinted orange, 30–60 seconds.
Add the softened unsalted butter to the sugar mixture and beat with a mixer on medium-high until very pale and fluffy, 3–4 minutes, scraping the bowl once.
Beat in the large eggs one at a time on medium speed, fully incorporating each before adding the next and scraping the bowl as needed, 1–2 minutes total.
In a small bowl, whisk the sour cream, vanilla extract, and the 2 tbsp orange juice (for batter) until smooth, then beat into the batter on low just to combine.
Add the dry ingredients in two additions, mixing on low until no dry pockets remain. Scrape the bowl and fold by hand a few times to ensure an even, thick batter; do not overmix.
Scrape the batter into the prepared pan and smooth the top. Bake until the top is deeply golden and a skewer inserted in the center comes out with a few moist crumbs (or an instant-read thermometer reads 200–205°F), 60–70 minutes. If the cake is browning too quickly, tent loosely with foil for the last 15–20 minutes.
Cool the cake in the pan for 15 minutes. Lift out using the parchment and transfer to a wire rack; cool until just slightly warm to the touch, about 30 minutes.
For the glaze, whisk the confectioners' sugar with the 3 tbsp orange juice (for glaze) until smooth and thick but pourable; adjust with a few drops more juice if needed. Spoon over the warm cake, letting it drip down the sides, and let set for about 20 minutes before slicing.