Season the trout fillets with salt and black pepper.
In a large skillet, melt 1 tablespoon of butter over medium heat.
Add the trout fillets, skin side down, and cook for 3-4 minutes per side, or until the fish is cooked through and flakes easily with a fork.
Remove the fillets from the skillet and set aside.
In the same skillet, melt the remaining tablespoon of butter.
Add the chopped onion and minced garlic. Sauté until the onion is translucent, about 5 minutes.
Pour in the white wine and fish or vegetable broth. Bring to a boil and cook for 5 minutes to reduce slightly.
In a small bowl, mix the flour with a bit of the hot liquid from the skillet to form a smooth paste.
Stir the paste into the skillet and cook for another 2-3 minutes until the sauce has thickened.
Stir in the heavy cream and cook for 2-3 minutes, until the sauce is creamy.
Add lemon juice and chopped parsley. Adjust seasoning with salt and black pepper.
Return the trout fillets to the skillet and spoon some of the sauce over the top.
Garnish with lemon slices and additional parsley if desired.
Enjoy your meal!