A couple of years ago, my SO got a Mexican cookbook (by Diana Kennedy). She loves cooking so she decided to cook the most elaborate dish she found in the cookbook: black mole. This mole was special because traditionally it is only made where there is a holiday. So she decided to invite all of her neighbors. We spent around 12 hours in the kitchen making this dish (plus a couple of hours looking for the ingredients). We were quite happy at the end because the mole was really good.