Prepping these burgers ahead is super cinchy: Make the caesar dressing and frico mixture up to 3 days in advance. Form the anchovy-garlic patties up to 2 days ahead of time. (Let sit outside of the fridge for an hour before cooking.) Day-of, you’ll just have to fire off burgers and slice some onions, basically. If you want to scale the recipe up to serve more, go for it! You’ll just have to cook in batches. Want to cook outdoors? Use your grill as you would your stovetop: Preheat your cast iron skillet on the grill grates for a solid 5-7 minutes. To determine if the skillet is hot enough, look for slight billows of smoke when you add the vegetable oil to your skillet before adding the patties.