Preheat oven to 350°.
To prepare garlic, combine 1/2 teaspoon kosher salt and garlic in a bowl. Place garlic mixture on a jelly-roll pan coated with cooking spray. Bake at 350° for 25 minutes or until browned, stirring occasionally.
To prepare shrimp, heat oil in a large nonstick skillet over medium-high heat. Add shrimp; sauté 3 minutes or until done. Remove shrimp from pan.
Melt butter in pan over medium heat. Stir in half-and-half, broth, cheese, 1/4 teaspoon salt, red pepper, and black pepper. Cook 1 minute or until cheese melts, stirring constantly. Stir in shrimp and spinach; cook 1 minute. Combine shrimp mixture, garlic mixture, and pasta in a large bowl; toss well. Serve immediately.