Heat olive oil in a large skillet over medium-high heat. Pat cod fillets dry with a paper towel and season both sides with salt and black pepper, to taste.
Add fillets to hot skillet and cook for 2-3 minutes, or until they become golden brown. Reduce heat to medium and carefully flip each fillet. Top each filet with an equal amount of herb butter and continue cooking for another 3-4 minutes. While cooking, spoon the herb butter back over the filets as it melts.