In a small saucepan, boil the blood orange juice until it is reduced to ½ cup. Add the zest, sugar and heavy cream and stir until combined and begins to lightly bubble. Remove from heat.
Temper the eggs by slowly drizzling ½ of the cream mixture into the eggs and whisking the eggs constantly. Slowly add the egg mixture back with the rest of the cream and mix well.
Strain everything through a fine mesh strainer and divide it into ramekins. Each ramekin should be about ⅔ pf the way full.
Place the ramekins in a baking pan and fill the baking pan with water until it is halfway up the sides of the ramekins. Cover the baking pan with aluminum foil.
Bake for about 45 - 60 minutes, or until the creme brulee is set. It should still jiggle in the center, but not be liquidy. Cool to room temperature, then refrigerate to completely set.
Once you are ready to serve, add the sugar to each ramekin, swirling to ensure the creme brulee has an even coating of sugar. Use your oven broiler or kitchen torch to caramelize the sugar. Serve immediately, or within the hour or else the sugar crust will soften and become chewy.
Notes
Do not add the sugar and brulee until you are ready to serve