Season fillets with salt and pepper, cover in flour and shake of excess. In medium-hot saute pan, add canola oil and cook bass until golden brown. Flip and add apple cider. Bring liquid to a boil and then add 2 tablespoons butter. Keep cooking until the bass is done, about 2 to 3 minutes, depending on the thickness of fish. Remove fish to platter and keep warm. Reduce cooking liquid until thick, season with salt and pepper and keep warm.
Prepare spinach. Heat very large saute pan until hot. Add butter, but do not let it burn. Add walnuts and saute for about 1 minute and then add spinach. Season with salt and pepper. Cook spinach until it begins to wilt, about 2 to 3 minutes only; drain well.
Other Notes
Divide spinich amond 4 plates. Place a piece of bass on top of spinach and drizzle apple cider reduction over fish. Enjoy!