Cook the spaghetti in boiling water according to package directions.

Heat the oil in a frying pan over medium heat.

Gently sauté the onion until it just begins to soften.

Add the scallops to the pan and cook, stirring occasionally, for three minutes.

Stir in the lemon juice and then the frozen peas and shrimp.

Add ⅓ cup cream and cook, stirring constantly, for a moment or two.

Add the cheese, pepper, tarragon and parsley and stir through until the cheese melts.

Taste for seasoning and add a little more cream if necessary to give the sauce a nice consistency.

Serve over the drained pasta.