2 cups sugar
Juice of ½ lemon
Pinch of cinnamon
Zest the oranges using a microplane. Remove the peel and any leftover pith (the white part) from the oranges but set it aside. You will need it to make the marmalade thicker. Make sure to get all the pith off the oranges or it will make the marmalade bitter.
Slice the oranges into half-moon slivers. Combine the orange slices, zest, sugar, lemon juice and 1 ¾ cups of water in a pot and bring to a boil over medium- high. Reduce to simmer over medium-low. Wrap the leftover pith in cheesecloth, tie it off and let it simmer in the orange mixture so that the pectin in the peel can thicken the marmalade. Stir frequently. At about 35 minutes, add the pinch of cinnamon and finely chopped rosemary. As it cools it will thicken. It will thicken more as it sets in the refrigerator.