Bring a pot of salted water to a boil.

Add shell pasta and cook until al dente.

Drain pasta and set aside.

In a saucepan, melt butter over medium heat.

Add flour and cook, stirring constantly, until light brown and nutty.

Gradually whisk in vegetable stock until smooth.

Stir over low heat until the sauce begins to thicken.

Stir in cream cheese, chives, and marjoram.

Season with salt and pepper to taste.

Set sauce aside and keep warm.

Heat olive oil in a separate pan over medium heat.

Sauté sliced zucchini for about 3 minutes.

Add finely diced garlic and cook for 2 minutes, until fragrant.

Season zucchini and garlic with salt and pepper.

Add tinned tuna (drained) to the pan and warm through.

Toss the zucchini and tuna mixture with the prepared sauce.

Add the cooked pasta to the sauce and tuna mixture and toss to combine.

Serve immediately.