Preheat the oven to 350°F (175°C). Grease a 9×5-inch loaf pan and set aside.
In a large bowl, whisk together the all-purpose flour, granulated sugar, baking powder, and salt until well combined.
In a separate medium bowl, whisk the melted unsalted butter, eggs, whole milk, freshly squeezed lemon juice, lemon zest, and vanilla extract until smooth.
Pour the wet ingredients into the dry ingredients and gently fold together with a spatula until just combined. Do not overmix; the batter should be slightly lumpy.
Pour the batter into the prepared loaf pan and smooth the top with a spatula.
Bake in the preheated oven for 45 to 50 minutes, or until a toothpick inserted into the center comes out clean.
Remove the bread from the oven and let it cool in the pan for 10 minutes.
Transfer the bread to a wire rack to cool completely before slicing and serving.