Cut enough young squash (about 4-6 depending on size) into roughly 1” cubes to make four cups, boil until just tender, drain, and set aside. Make two cups of white sauce with whole milk and butter, add about a cup of sour cream, a half cup fresh-grated/shaved Parmesan, and a lightly beaten egg. Stir in two cups cooked young limas, a half cup of minced white onion, and mix with squash. Add salt and white pepper to taste, and stir gently. Top with more Parmesan and bake at 350 until lightly browned and bubbling. A lot of people use dill in this recipe, but just don’t.
