Cook pasta shells according to package. Meanwhile, heat butter in a large sauté pan over medium-high heat. Add sliced shallot and crushed red pepper; reduce heat to medium-low, and cook for 1-2 minutes or until translucent. Add spinach and chicken broth; cover and cook for 1 minute. Add half-and-half, 1/4 cup grated pecorino Romano cheese, and black pepper. Stir to combine, and cook for 3 minutes. Add grape tomatoes, halved lengthwise, and the cooked pasta; toss. Garnish with flat-leaf parsley and additional grated cheese. Serve.