Preheat your oven to 350°F (175°C). Line a 9×5-inch loaf pan with parchment paper, leaving a 1-inch overhang on both long sides. Lightly spray with non-stick cooking spray and set aside.

Add the granulated sugar and lemon zest to a large mixing bowl. Rub them together with your fingertips for about 30 seconds until the sugar turns pale yellow and smells intensely fragrant — this releases the citrus oils directly into the sugar and distributes lemon flavor through every bite.

Add the 3 room-temperature eggs to the lemon sugar and whisk vigorously for 1–2 minutes until the mixture is pale and slightly thickened. Add the sour cream, melted butter, oil, lemon juice, lemon extract, and vanilla extract. Whisk until the batter is smooth, glossy, and uniform.

In your second bowl, whisk together the flour, baking powder, baking soda, and salt. Pour the dry ingredients into the wet ingredients all at once. Using a rubber spatula, fold gently with large sweeping strokes from the bottom upward, stopping the moment no dry flour streaks remain. Do not overmix.

Pour the batter into your prepared loaf pan and smooth the top with your spatula. Tap the pan firmly on the counter once to release air bubbles. Bake on the center rack for 50–60 minutes, or until the top is deep golden brown and a toothpick inserted in the center comes out with only a few moist crumbs. If the top browns too quickly, loosely tent with aluminum foil at the 35-minute mark.

Let the loaf cool in the pan for 15 minutes, then use the parchment overhang to lift it onto a wire cooling rack. Allow it to cool completely — at least 1 hour to 90 minutes — before glazing.

Sift the powdered sugar into a medium bowl. Add 2 tablespoons of fresh lemon juice and 1 tablespoon of milk. Whisk until completely smooth and silky. The glaze should fall from the whisk in a slow, thick ribbon. If too thick, add lemon juice ½ teaspoon at a time; if too thin, add powdered sugar 1 tablespoon at a time. Stir in lemon extract if using.

Place the fully cooled loaf on the wire rack set over a parchment-lined tray. Pour the glaze slowly down the center, then gently guide it over the sides with a spatula. Let the glaze set at room temperature for 20–30 minutes before slicing and serving.