1. Preheat the oven to 400°F (200°C).

2. Place the cod fillets in a baking dish. Coat both sides with olive oil, then season with kosher salt and ground black pepper.

3. Bake for 14 to 15 minutes, until the cod looks opaque and flakes easily with a fork. Check for an internal temperature of 145°F (63°C), if desired.

4. Meanwhile, melt 1 tablespoon of the butter over medium heat.

5. Add the shallots and whisk for about 30 seconds.

6. Add the dry white wine, white wine vinegar, and fresh orange juice. Whisk while the mixture reduces until roughly 2 tablespoons of liquid remain.

7. Stir in the heavy cream and kosher salt, then bring the mixture to a boil.

8. Reduce the heat to medium-low and add the orange zest.

9. Gradually whisk in the remaining cold butter a few pieces at a time. Whisk continuously until the sauce becomes smooth and silky.

10. Plate the baked cod, spoon the orange beurre blanc over each fillet, and serve immediately.