Season the salmon fillets with salt and pepper on both sides.

In a large skillet, melt 1 tablespoon of butter over medium heat. Once hot, carefully place the salmon fillets skin-side down in the skillet. Cook for about 4-5 minutes until golden brown, then flip to sear the other side for another 3-4 minutes. Remove the salmon from the skillet and set it aside.

In the same skillet, add the remaining tablespoon of butter. Add the sliced mushrooms and sauté for about 2-3 minutes until softened. Add the garlic and cook for another minute, stirring until fragrant.

Throw in the fresh spinach and cook until wilted, which should take about a minute.

Pour in the heavy cream, stirring well to combine with the vegetables. Bring it to a gentle simmer and let it cook for an additional 2-3 minutes. Season with salt and pepper to taste.

Return the salmon fillets back into the skillet and spoon some of the creamy sauce over them. Let them cook together for an additional minute to warm through. Garnish with fresh parsley before serving.