Preheat Dutch oven or other heavy pot over medium heat.
Add oil and 2 Tablespoons of the butter (reserving the other 1 Tablespoon for later).
Start pasta according to package directions.
Add salmon, skin side down, and cook for 2 minutes.
Turn heat down to low-medium and flip salmon over.
Remove skin from salmon (and bottom of pan if necessary). Cook salmon 3 minutes longer.
Add raw shrimp, garlic, marjoram, and basil and cook another 5 minutes, breaking up salmon into pieces.
Note: If using cooked shrimp, add at the end of this 5-minute cook time.
Turn heat to low, and add remaining 1 Tablespoon of butter and melt.
Add cream, cream cheese, salt, and black pepper.
Heat on low 5-10 minutes or until cream cheese is melted, stirring often.
Add drained pasta and combine.