Preheat oven to 350°F. Peel onions and cook in boiling, salted water, that contains a dash of lemon juice or vinegar, until onions are tender. Cook celery in separate pan. Drain vegetables well. Melt butter or margarine, over low heat. Add flour, salt, pepper, and nutmeg. Cook gently, stirring until mixture is bubbly all over. Slowly add milk and light cream and cook gently, stirring until thickened. In buttered casserole, arrange layers of onions, celery and almonds. Pour cream sauce over vegetables and sprinkle top with paprika. Add Parmesan cheese to the topping if you like. Bake at 350°F about 20 minutes, if food was hot when it went into the oven, or until sauce is bubbly and brown. Serves 6.