Bring a large pot of salted water to a boil. Wash and dry produce.

Peel and mince or grate garlic. Trim and thinly slice scallions, separating whites from greens. Mince dill. Dice tomato into ½-inch pieces. Quarter lemon.

Once water is boiling, add spaghetti to pot. Cook, stirring occasionally, until al dente, 9-11 minutes. Reserve 1 cup pasta cooking water (1½ cups for 4 servings), then drain.

Meanwhile, heat a drizzle of olive oil in a large pan over medium-high heat. Add garlic, scallion whites, oregano, salt, and pepper. Cook, stirring, until fragrant and slightly softened, 1 minute.

Reduce heat to medium; stir in stock concentrates, cream cheese, half the dill, half the feta, and ⅓ cup pasta cooking water (½ cup for 4 servings). (Ladle straight from the pot if pasta hasn’t finished cooking yet.) Cook, stirring and smashing feta with the back of a spoon or spatula, until sauce is creamy and thickened, 2-3 minutes.

Stir in tomato and spinach (add in batches if necessary). Cook, stirring, until tomato is softened and spinach is wilted, 2-3 minutes. Taste and season with salt and pepper. Remove from heat.

To pan with sauce, stir in spaghetti, a drizzle of olive oil, a squeeze of lemon juice, and as much remaining dill as you like; toss until thoroughly coated. TIP: If needed, add another drizzle of olive oil and reserved pasta cooking water a splash at a time until pasta is thoroughly coated in sauce.

Divide pasta between bowls; top with scallion greens and remaining feta. Serve with any remaining lemon wedges on the side.