Storage: Keep in an airtight container at room temperature for up to 2 days, or refrigerate up to 5 days. Freezer-friendly: Wrap muffins individually and freeze up to 3 months; thaw at room temperature. Variations: Swap poppy seeds for chia seeds (same amount), or fold in 1 cup blueberries for lemon blueberry muffins. Tip: Avoid overmixing to keep muffins tender.