Add the onion to the skillet and cook 3 to 4 minutes until softened. Stir in the garlic, sun-dried tomatoes, and paprika. Cook 1 minute, stirring frequently.
Pour in the chicken broth and heavy cream. Stir in the Dijon mustard and bring to a gentle simmer. Cook 3 to 4 minutes until the sauce thickens slightly.
Add the butter and stir until melted and the sauce is smooth and glossy. Taste and season with salt and pepper if needed.