Season both sides of the salmon fillets with salt and pepper.
Heat 2 tablespoons olive oil in a large skillet over medium heat until shimmering.
Place the salmon in the skillet skin-side down and cook about 7 minutes, then flip and cook 3 more minutes, until just barely pink in the center; transfer salmon to a plate and set aside.
Add the minced garlic to the same skillet and cook 1 minute until fragrant, stirring so it does not burn.
Pour in 1 cup heavy cream and 1/2 cup chicken broth, then stir in 1 teaspoon garlic powder, 1 teaspoon Italian seasoning, and 1/2 cup Parmesan cheese.
Whisk in 1 tablespoon cornstarch until fully incorporated, then simmer the sauce 1–2 minutes until it begins to thicken.
Add 1 cup chopped spinach and 1/2 cup sun-dried tomatoes to the sauce and simmer until the spinach wilts and the sauce is heated through.
Return the seared salmon to the skillet and spoon the sauce over the fillets; heat 1–2 minutes to warm the fish before serving.