Mix the oats, brown sugar, baking powder, salt, and ginger in a large bowl. Sift until blended.
Add the lemon zest, and mix to distribute evenly.
In a second bowl, beat the eggs lightly, then add the oil and milk.
Add the lemon juice last to the egg mixture, and then stir the wet ingredients into the dry.
Cover the bowl, and refrigerate for about 15 minutes. This allows the flavors to blend more thoroughly.
When it’s ready, preheat the oven to 350°F, and lightly grease an 8” x 8” baking pan.
Transfer the batter to the baking pan, and spread it out evenly.
Bake in the oven for 20 to 30 minutes. The outer edges should begin to brown, and the middle should be firm.
Remove from the oven, and cut into bars.