Preheat the oven to 400°F (200°C). Pat the salmon filets dry and season both sides with salt and black pepper.

Place an oven-safe skillet over medium-high heat. Add 1 tablespoon salted butter and let it melt. Add the fresh thyme leaves and the 4 lightly smashed garlic cloves and cook 30–45 seconds until fragrant.

Add the salmon to the skillet (skin-side down if using skin). Sear 2–3 minutes without moving to develop color, then carefully flip and sear the other side 1–2 minutes. Remove the salmon from the skillet and set aside on a plate.

Reduce the heat to medium. Add the remaining 3 tablespoons salted butter to the same skillet. Add the thinly sliced shallot and a pinch or two of chili flakes and cook, stirring, about 2 minutes until the shallot is softened.

Using a fork, press the cooked garlic cloves in the skillet to mash them into a coarse paste, then pour in the 1 cup heavy cream and the 1/3 cup salsa verde. Stir and bring to a gentle simmer, stirring until the mixture is smooth and slightly thickened.

Stir in the 1 cup grated Parmesan cheese, the 1/2 cup chopped sun-dried tomatoes, and the 3 cups fresh baby spinach. Cook, stirring occasionally, until the Parmesan has melted and the spinach is wilted, about 3–5 minutes.

Return the salmon to the skillet, spooning some sauce over the tops. Sprinkle the 1 tablespoon lemon juice over the salmon, then transfer the skillet to the preheated oven and bake 6–8 minutes, or until the salmon is cooked to your desired doneness.

Remove the skillet from the oven. Mix the 1 tablespoon lemon zest with the 2 tablespoons chopped fresh dill and the 1/4 cup chopped green onions, then sprinkle that mixture over the salmon. Serve the salmon in the cream sauce.