In a large skillet, heat 2 tablespoons of butter and 2 tablespoons of olive oil over medium heat until melted and hot.

Season the cod cubes with salt and pepper. Add the cod to the skillet in a single layer, cooking for about 3-4 minutes on each side, or until golden brown and cooked through. Remove the cod from the skillet and set aside.

In the same skillet, reduce the heat to low and add the remaining 2 tablespoons of butter. Once melted, stir in the minced garlic and cook for about 30 seconds until fragrant.

Pour in the heavy cream, lemon zest, lemon juice, and Dijon mustard. Stir to combine and let the sauce simmer gently for 3-4 minutes until it thickens slightly.

Add the chopped dill to the sauce, stirring well to incorporate. Season with additional salt and pepper to taste.

Return the cooked cod to the skillet, gently tossing to coat the fish with the dill cream sauce. Allow to heat through for 1-2 minutes.

Serve the cod cubes warm, garnished with fresh dill sprigs and lemon wedges on the side.