Preheat oven to 350F. Measure and combine 1¼ cups of sugar, semolina flour, almond flour, and the blood orange zest in a large mixing bowl.
In a separate bowl, combine the Greek yogurt, eggs, and melted butter.
Add the wet ingredients to the dry ingredients and stir to combine. Butter a round cake pan and add the batter to the pan.
Bake at 350F for 40 - 50 minutes, just until the center of the cake springs back when you press on it. The cake is very dense, so it may take more time depending on your oven.
Make the sauce by combining ¾ cup Campari, ¾ cup sugar, and the juice of 4 blood oranges in a small saucepan. Bring to a boil, then reduce the heat and simmer until it begins to thicken.
To assemble the cake, turn the cooled cake out of the cake pan and drizzle with Campari syrup. Top with candied blood oranges or another garnish of your choosing.