Preheat the oven to 400°F. Grease and flour a 9 x 5-inch baking pan.
In one bowl, mix together the flour, sugar, baking powder, salt, and lemon zest.
In a separate bowl, beat together the eggs, milk, oil, two tablespoons of lemon juice, and vanilla.
Mix the wet ingredients into the dry. There should be plenty of lumps in the batter.
Squeeze the zucchini of some of its liquid and gently fold into the batter.
Pour in the batter into the baking pan.
Bake in the middle oven rack for 20-25 minutes, or until a toothpick inserted in the middle comes out clean.
Remove from the oven and run a knife along the edges. Leave to cool for 15 minutes, then take out the loaf from the pan and place on a wire rack to cool completely.
Whisk together the remaining lemon juice, powdered sugar, and milk until it forms a loose paste. Brush over the cooled bread.
Notes
The recipe easily doubles for extra loaves.
Make sure zucchini is squeezed of some of its excess moisture to prevent the bread from becoming dense.
Lemons are more easily juiced when they are at room temperature. After zesting the lemon, roll it under your palm on the counter to help encourage the juices to release when you squeeze it.