Preheat oven to 375. Lightly spray a 9 x 13 baking dish with cooking spray.
Cook pasta according to package directions. Drain well.
Combine flour and salt in a Dutch oven over medium heat. Gradually add milk, stirring constantly with a whisk, bring to a boil. Cook until slightly thick ( about 1 minute) stirring constantly with a whisk. Remove from heat and stir in 1 ¼ cup cheese until melted.
Heat butter in a large nonstick skillet over medium-high heat. Add shrimp and garlic, sauté 3 minutes. Stir in wine and pepper, and cook until shrimp is done.
Add pasta, shrimp mixture and peas to cheese mixture, tossing well to combine. Spoon pasta mixture into baking dish and sprinkle with remaining cheese. Bake at 375 for 20 min- 30 min. (Until cheese melts and begins to turn brown.)