Combine the cream cheese, feta, and chopped baby spinach into a mixing bowl. Mix until it becomes semi smooth. It will be quite thick. Set aside.

Lay out the flounder fillets, pat dry, and sprinkle seasoning onto each fillet.

Divide the stuffing into 4 equal portions. Add a small "ball" of the stuffing close to the tail of the fish. Then starting from the tail, roll each fillet and place it seam side down on the baking dish. If it needs, you can place a toothpick into it to hold.

Sprinkle more seasoning on top and drizzle olive oil over the fillets.

Bake at 350ºF for about 20 minutes, until the fish is cooked through.