To make and bake the bread, in a large bowl whisk together the flour, oats, granulated sugar, brown sugar, baking powder, soda, cinnamon, salt, walnuts, and chocolate chips. In a small bowl, whisk together the buttermilk, egg and melted butter. Stir the wet mixture into the dry ingredients and stir with a wooden spoon or rubber spatula just until evenly moistened; the batter will be lumpy.
Pour the batter into a greased and floured 9X5-inch loaf pan and bake at 350 degrees F until a knife or toothpick inserted in the middle comes out clean, about 40-45 minutes.
To assemble the bread in a jar for a gift, layer the dry ingredients in the order listed into a quart-sized jar, packing down each layer (or lightly tapping the jar on the counter to help the ingredients settle). Start with the flour and layer the ingredients through the chocolate chips. Attach labels (located here to download) to the front and back of the jar. The mix will keep for 2-3 months at cool room temperature.