Place cranberries, sugar and orange juice into a saucepan and bring to a boil while stirring constantly. Simmer for about 10 minutes or until thickens. Add orange zest, stir to combine and remove from heat. Reserve 3 tbsp of cranberry sauce to use for cocoa brownie.
Dissolve gelatin in orange juice and let it swell for 5-10 minutes.
Add the bloomed gelatin to the warm cranberry sauce and stir until completely dissolved. Let cool.
Prepare cocoa cranberry brownie
Preheat the oven to 350F (180C). Grease and line an 8-inch (20cm) springform pan with parchment paper.
In a bowl whisk egg with sugar until well combined. Incorporate oil and vanilla extract. Add the reserved 3 tablespoons of cranberry sauce and mix to combine.
Sift the flour, salt and cocoa powder and whisk to fully incorporate.
Pour the batter into the prepared pan.
Bake for 10-12 minutes until a toothpick inserted into the center comes clean or with few moist crumbs attached.
Let cool completely.