Adjust rack to top position and preheat oven to 425 degrees. Bring a large pot of salted water to a boil. Wash and dry produce.

Once water is boiling, add cavatappi to pot. Cook, stirring occasionally, until al dente, 9-11 minutes. Reserve 1 cup pasta cooking water (2 cups for 4 servings), then drain.

While pasta cooks, core and dice green pepper into ½-inch pieces. Trim and thinly slice scallions, separating whites from greens.

Heat a drizzle of oil in a large pan over medium-high heat. Add green pepper and scallion whites; cook, stirring occasionally, until slightly softened, 3-4 minutes. 

Add plant-based protein and cook, stirring, until veggies are browned, 2-3 minutes more. TIP: If plant-based protein starts popping, cover pan with a lid.

Using a slotted spoon, transfer plant-based protein mixture to a large bowl. Add cream cheese, Mexican cheese blend, and ¼ cup reserved pasta cooking water (½ cup for 4 servings); toss to combine. 

Add drained cavatappi to bowl; toss to evenly coat. TIP: If needed, stir in more pasta cooking water a splash at a time until everything is coated in a creamy sauce. 

Transfer pasta mixture to an 8-by-8-inch baking dish (9-by-13-inch baking dish for 4 servings); evenly sprinkle with Monterey Jack.

Bake on top rack until cheese melts and sauce is bubbling, 3-5 minutes.

Top pasta bake with scallion greens. Divide between plates or serve family style directly from dish.