Set oven to 350°F (175°C). Grease and flour an 8x4-inch loaf pan.
Using a stand mixer, beat butter and sugar until pale and airy, about 2–3 minutes. Incorporate vanilla, lemon juice, lemon zest, and eggs; blend until uniform.
In another bowl, whisk flour, salt, and baking powder. With mixer on low, add dry mixture alternately with milk, mixing until just incorporated.
Fold in cranberries by hand until evenly distributed. Transfer batter to the pan and bake for 60 minutes, until a toothpick inserted in the center emerges clean.