Preheat oven to 350° F. Grease two loaf pans. In a very large bowl, stir together the flour, sugar, lemon zest, baking powder, salt, cinnamon, and nutmeg. In a medium bowl, lightly beat the eggs. Whisk in oil, milk, and maple syrup. Add to flour mixture; stir to combine (batter will be stiff). Stir in cranberries and walnuts. Divide batter between pepared pans; spread evenly.
Bake about 60 minutes or until a toothpick inserted in the center comes out clean. Let stand in pans on a wire rack 10 minutes. Remove loaves from pans. Cool completely on wire rack. Wrap loaves in foil or plastic wrap and store overnight before slicing.