Real estate agents tell you that, when you are selling your house, you should bake chocolate chip cookies to fill the air with that tantalizing aroma. For me, it's the scent of cinnamon that makes my house feel like home, and that's what I was craving when I baked these cinnamon buttermilk muffins. Determined to use every drop of the quart of buttermilk I bought for this orange Bundt cake, I've made salad dressings and sauces, and still I have a cup of buttermilk left. You can add anything to this batter: fresh or dried fruit, chocolate chips, lemon or orange zest. Serve these light and fluffy muffins for breakfast, or with an afternoon cup of tea.