Melt 2 tbsp butter in large skillet over medium heat. Stir and cook until shrimp turns pink, about 4-6 minutes. Remove from pan and set aside.
Add and melt 4 tbsp butter to skillet. Whisk in flour. Let bubble for 2 minutes then add white wine, lemon juice, and milk. Bring to a boil, stir until thick. Add garlic salt to taste.