Begin by prepping all your ingredients. Chop one large yellow onion and mince three cloves of garlic. Season the four salmon fillets with salt and freshly ground black pepper, ensuring they're coated evenly.

In a large skillet, heat two tablespoons of olive oil and one tablespoon of unsalted butter over medium-high heat until shimmering. Carefully add the seasoned salmon fillets to the skillet, searing them for about 3-4 minutes on each side until golden brown and cooked through.

Using the same skillet, add the chopped onion and sauté for 2 minutes until it becomes translucent. Then, add the minced garlic, one anchovy fillet, and your fresh chili or red chili flakes. Cook everything together for another minute.

Pour in one cup of chicken broth, scraping up any browned bits from the bottom of the skillet. Let this mixture simmer for about 2 minutes. Next, add one can of crushed tomatoes and continue simmering for an additional 5 minutes until the sauce thickens slightly.

Slowly stir in three cups of fresh spinach to the skillet. Cook for about 2 minutes or until the spinach wilts down, blending beautifully into the rich sauce.

Return the seared salmon fillets to the skillet, spooning the sauce generously over each piece. Sprinkle 1/4 cup of grated Parmesan cheese over the top. Cook everything together for an additional 3 minutes.

Garnish your savory salmon all’Arrabbiata with additional black pepper and chopped parsley. Serve with red pepper flakes on the side for those who enjoy an extra kick.