For a spicier kick, leave the seeds in half of the jalapeños. Feel free to substitute cheddar cheese for Monterey Jack for a sharper flavor. These muffins are best enjoyed fresh, but can be stored in an airtight container at room temperature for up to 2 days. For best results, ensure the buttermilk is well-shaken and the butter is cooled slightly to prevent cooking the eggs. Make sure all ingredients are finely minced