Grate the lemon zest as fine as possible. Save the lemons for something else.
In a large bowl, whisk together the lemon zest, sugar and eggs.
Whisk in the milk, vanilla and salt.
Pour the custard into the buttered baking pan. Bake at 350* for approximately 25 minutes. The center will be slightly soft. Residual heat will finish cooking the custard. Don’t over cook. Cool 20 minutes before serving warm. Store in the fridge.