Rinse the cranberries thoroughly and set them aside to dry. Reserve 1/2 cup of cranberries to add later for added texture.
Zest and juice half of a fresh orange. Rinse the orange before zesting.
In a large pot, combine brandy, water, orange juice, and sugar. Bring the mixture to a boil, stirring occasionally until the sugar is completely dissolved (about 5 minutes).
Add 11 1/2 ounces of cranberries (reserving the 1/2 ounce for later), cinnamon, and orange zest to the pot. Cook uncovered on medium-high heat until the cranberries burst, which takes about 10 minutes.
Turn off the heat, but keep the pot on the hot burner. Use a potato masher or wooden spoon to further crush the cranberries until a thick sauce forms.
Add the reserved 1/2 ounce of cranberries and cover the pot. Leave it on the still-hot burner for about 5 minutes to soften the whole cranberries, adding texture to your sauce.
Transfer the sauce to a serving bowl and allow it to cool before serving.