Preheat the oven to 325. Using a teaspoon of the blood orange olive oil, grease a 9 x 13" baking pan. Line the pan with a strip of parchment, cut to overhang the long sides of the pan.
In a large bowl set over a double boiler, slowly melt the butter with the dark chocolate. Stir constantly until completely melted. Remove from the heat and stir in the blood orange fused olive oil, eggs, tangerine balsamic, orange zest and sugar. Mix until well combined. Whisk together the flour and cocoa powder and add to the wet ingredients. Fold until there are no visible dry spots.
Scrape the batter in to the prepared baking pan. Bake on the center rack of the oven for approximately 30 minutes or until a tester inserted in the center comes out with very moist crumbs adhering. Allow to cool in the pan for 15 minutes and then lift out using the parchment and cool completely before cutting.