Bring large stockpot of water to boil; add pasta. Cook 8 minutes; pasta should be a bit underdone. Drain, rinse under cold water, and drain again. Add pasta to large mixing bowl and set aside.
Preheat oven to 400°F. Remove shrimp from freezer and set in bowl of cold water to thaw. Peel and devein shrimp as soon as defrosted enough to handle (but not fully defrosted) and add to bowl with pasta.
In small bowl, combine 1/3 cup feta, half of lemon zest, panko bread crumbs and 2 tablespoons parsley. Mix well and set aside.
To make sauce, melt butter in small sauce pan over medium heat. Add flour and stir until flour is absorbed by butter to form a paste. Cook, stirring, for 1 minute. Add milk and stir vigorously with a wire whisk to remove any lumps. Continue to cook over medium heat, stirring frequently, for 5 minutes or until sauce thickens enough to coat back of wooden spoon.
Remove pan from heat and whisk in gouda cheese and remaining feta cheese. Whisk until sauce is smooth; the gouda will melt completely and feta will be well incorporated. Add remaining lemon zest, remaining parsley, dill weed, and salt and pepper to taste. Pour sauce over pasta and stir to combine.
Pour mixture into 9×13-inch casserole dish. Sprinkle panko bread crumb mixture over top. Place dish on middle rack in oven and bake 25 minutes, until top is browned and cheese is bubbling. Remove from the oven, let sit for 5 minutes, serve hot.
*Shrimp are sold by the number per pound; this recipe calls for 31-40 size, which are often labeled “large.” For a delicious vegetarian version of this recipe, omit the shrimp.