You can prepare, shape and score, wrap tightly and freeze up to 3 months. When ready, place it seams down on a large baking sheet. Brush with melted butter and sprinkle with nutmeg. Bake at 400F for 25-30 minutes or until golden brown.
Preheat oven to 400°F In a medium skillet, cook ground meat and onion over medium-high heat until browned. Drain off fat. Stir in cheese, spinach, milk, lemon peel, salt and 1/4 teaspoon nutmeg.
Unroll phyllo, cover with plastic wrap. Remove one sheet and lightly brush with butter. Place a second sheet on top; brush with butter. Add four more sheets, one at a time, brushing each with butter. Spread half the filling over the phyllo stack, spreading to within 3 inches of long sides and 1 1/2 inches of short sides. Fold short sides of phyllo over the filling. Fold one long side of phyllo over filling, then roll up. Repeat to make second roll.
Place phyllo rolls, seams down, on a large baking sheet. Brush with remaining melted butter; sprinkle with nutmeg. Score the tops, making cuts 1 inch apart and 1/4 inch deep.
Bake 15-18 minutes or until golden brown. Let stand 15 minutes, slice on the scored lines.