Heat the oven to 350°F. Grease a standard 9x5 loaf pan.
Mix milk and lemon juice or vinegar togther and leave to coddle.
Whisk together the flour, sugar, baking powder, baking soda, salt and cinnamon in a medium mixing bowl.
Peel, core, and chop the apples. Toss in with the flour mixture until well coated.
Whisk the egg with the coddled milk and the oil.
Pour the liquid ingredients over the dry ingredients. Gently stir and fold the ingredients until all the flour has been incorporated and a shaggy, wet batter is formed. Be careful not to over-mix.
Scrape the batter into the prepared pan and pat it into the corners. Bake for 45-50 minutes. When finished, the loaf should be domed and golden, and a toothpick inserted into the center should come out clean. Let the loaf cool in the pan for 15 minutes before removing and slicing.
After they are completely cooled, wrap baked loaves tightly in plastic wrap and store at room temperature. (I just use the cheapest gallon size twist-tie type food storage bags.) Baked loaves can also be wrapped in plastic and aluminum foil and frozen for up to three months.
I've been thinking of making this with an additional 3 ounces of milk (so milk & vinegar total 1 1/2 cups) as it can get a bit dryish if not eaten within one day, which happens as several of us are obliged to be gluten or grain free, but haven't done so yet.