Preheat oven to 350°F and lightly spritz a 13×9-inch baking pan or casserole dish with cooking spray.
Place brownie mix, oil, water, and eggs in a large bowl and whisk until blended.
Pour the brownie batter into the prepared baking pan and spread out evenly along the bottom.
Place cream cheese in the bowl of an electric mixer fitted with the whisk attachment. Whisk on medium until fluffy, about 2-3 minutes.
Slowly add the sweetened condensed milk and continue to whisk until blended.
Add the vanilla to the bowl and whisk on low, gradually increasing the speed, until thoroughly combined.
Pour the cheesecake batter over the brownie layer and spread to the edges, creating an even layer.
Dollop the jellied cranberry sauce over the cheesecake layer and, using a toothpick or skewer, swirl to create a marble pattern.
Place in the oven and bake for 35-45 minutes or until cooked through. Check doneness by inserting a toothpick into the center of the brownie, if the toothpick comes out clean your brownie is done.
Remove from the oven and set aside to cool on a wire rack. Once cooled to room temperature, cover, and place in the refrigerator to set and firm-up further, about 1-2 hours.
While the cheesecake brownie is cooling, place water and 1 cup of sugar in a medium saucepan. Bring to a low simmer over medium-low heat and cook, stirring occasionally, until the sugar has dissolved.
Remove the simple syrup from the heat, stir in the fresh cranberries, and set aside to steep for 10 minutes.
Using a slotted spoon, remove the cranberries from the syrup, and set aside on a wire rack-line baking sheet to drain and dry, approximately 15 minutes.
Once dry, yet still sticky, place the cranberries in a zipper baggie with the remaining 1 cup of sugar, shake to coat.
Once the cheesecake brownie has chilled and set, remove from the refrigerator, and portion into squares. Garnish with candied cranberries before serving.