Chop off the roots and remove the greener tougher parts. You can keep the latter aside to make a soup later. Then chop the leeks into 1 inch thick pieces. Rinse them very carefully under wold running tap water. Make sure those pieces stay intact!

Peel the garlic clove and slice it in half. In a large non-stick pan (preferably one that is oven-proof, with a lid) add a splash of olive oil and the garlic. Season with pepper and salt. Then place the pan over medium-high heat.

Then fry the leeks for 5 to 6 minutes until the bottom part starts to turn brown. Carefully turn the leeks onto their uncooked side. Cook for another 4 to 5 minutes. Season with pepper again. Then pour in the pilsner beer.

Turn the heat up high until boiling. Then turn the heat down to a simmer and cover the pan. Let the leeks cook for 10 minutes. Remove the lid and then let the remaining juices evaporate. Now if your pan is fit to put in the oven, just leave the leeks inside. If not, carefully transfer the leeks to a large baking dish. Then sprinkle with the cheese and panko. Season with some pepper and salt.

Bake the leeks under a preheated grill for 3 to 4 minutes until the cheese has melted and the panko starts to turn brown. Then remove the leeks au gratin and let it cool for 2 minutes. Serve.