Preheat your oven to 175°C (350°F). Grease the loaf pan with butter and line it with parchment paper for easy removal.
In a large mixing bowl, whisk together the flour and baking powder until evenly combined. Set aside.
Zest both lemons directly into a separate bowl, then juice them and measure out 1/2 cup of lemon juice. Add the lemon zest to the bowl with the eggs and sugar.
In the same bowl, add the eggs and whisk vigorously until the mixture is pale and slightly frothy, fragrant with lemon zest.
Pour in the Greek yogurt and oil (or melted butter), then whisk again until the batter is smooth and well combined. The mixture should look glossy and slightly thickened.
Stir the lemon juice into the batter, folding gently until fully incorporated. The batter will be bright yellow and slightly bubbly.
Pour the wet ingredients into the bowl with the dry ingredients. Using a spatula, fold gently until just combined, being careful not to overmix—lumps are okay.
Transfer the batter into your prepared loaf pan, smoothing the top with the spatula for an even surface.
Bake in the preheated oven for 45-50 minutes, or until the top is golden and a toothpick inserted into the center comes out clean.
Once baked, remove the loaf from the oven and let it cool in the pan for about 10 minutes, then transfer to a wire rack to cool completely.
Slice the loaf once cooled, and enjoy the moist, tender crumb with a bright lemon aroma in every bite.
