Pat the salmon fillets completely dry with paper towels. Season both sides with garlic powder, onion powder, kosher salt, and freshly cracked black pepper.

Heat 1 tablespoon of olive oil in a large heavy cast-iron skillet over medium-high heat until shimmering hot.

Add the salmon fillets skin-side down (or flesh-side down if skinless) and sear undisturbed for 4 to 5 minutes until crisp and golden. Gently flip and sear the other side for 3 to 4 minutes until almost cooked through. Transfer salmon to a warm plate.

Reduce heat to medium. In the same skillet, melt 2 tablespoons of butter and sauté minced garlic for 60 seconds until fragrant and golden.

Pour in the broth and fresh lemon juice, scraping up all the savory browned bits from the bottom of the skillet. Bring to a rapid simmer for 2 minutes to reduce slightly.

Stir in heavy cream, lemon zest, and capers. Simmer gently for 2 to 3 minutes until the sauce turns velvety and coats the back of a spoon.

Toss in the baby spinach and fresh chopped dill, stirring gently for 60 seconds until the spinach just begins to wilt.

Nestle the seared salmon fillets back into the bubbling sauce along with lemon slices. Spoon the warm lemon cream over the fillets and heat for 1 minute. Garnish with fresh dill sprigs and serve immediately.