Place the blood orange juice in a 2-quart saucepan, bring to a boil, then reduce heat to medium and reduce the juice to 3/4 cup. When the juice is reduced remove it from the heat. And allow it to cool slightly. Place a medium sized bowl with a fine mesh strainer near the stove.
In a 3-quart saucepan combine the whole eggs, the egg yolks, and sugar and whisk to thoroughly combine. Slowly stream in the blood orange juice, whisking constantly until all the juice is added. Add the butter and place the pan over medium heat. Whisk constantly until the curd is thickened and is 185 degrees F.
Strain the curd through the fine-mesh strainer when it is done.
If you're using the curd right away pour the curd into the tart shell and use an offset spatula to smooth the surface. Place the tart pan on a wire rack set in a rimmed baking sheet and bake for 10 minutes.
If making the curd 1 or 2 two days in advance, press a piece of plastic wrap directly onto the surface of the curd, and refrigerate until ready to use. The curd can be refrigerated for up to 3 days. Let the curd sit for 30 minutes at room temperature before filling the tart shell.
After baking the curd in the tart shell allow it to cool to room temperature and then refrigerate for at least two hours before adding the whipped crème fraiche.