In a shallow bowl, combine flour, salt, pepper, garlic powder, and dried parsley.
Pat cod fillets lightly with paper towel to dry. Put the fish in the flour mixture to lightly coat both sides, shaking off excess.
Heat olive oil and 2 tablespoon butter in a large skillet (I like to use stainless) over medium heat.
Put cod fillets in skillet and cook for 3-4 minutes per side, until golden and just cooked through. Remove to a plate and keep warm.
If using, add white wine to skillet and scrape up browned bits with a wooden spoon. Let it simmer 1-2 minutes to reduce slightly. If not using wine, add lemon juice now and use a wooden spoon to scrape up browned bits.
Add lemon juice (if not yet added), chicken or vegetable broth, and capers and simmer for 3-4 minutes to reduce slightly.
With heat on low, whisk in remaining 4 tablespoon butter, 1 tablespoon at a time until the sauce is glossy. Taste and add more salt if desired.
Gently nestle the cod back into the pan and spoon sauce over the top. Simmer 1–2 minutes to warm through. Sprinkle fresh parsley over the top. I like to add red pepper flakes, too.
Serve cod piccata over angel hair pasta, orzo, couscous, or the side of your choice.