Rinse the mussels under cold running tap water. Brush them clean and scrape off any sediments on the shells using a sharp knife. Then rinse the mussels again and let them drain at room temperature.

Add the butter and garlic to a saucepan. Place this over medium heat. Gently fry the garlic for 2 minutes.

Then add the diced carrot, celery and onion. Season with pepper.

Stir the vegetables well. Cook them in the butter for 6 minutes. Then pour in the tripel beer.

Stir and cook for another 2 minutes. Add the cleaned mussels.

Stir and put a lid on the pan. Turn the heat up high now. Let the mussels cook in the beer and vegetables for 5 minutes. They should have opened by then. Add the crumbled blue cheese.

Stir and turn the heat lower. Let the blue cheese melt into the beer sauce. Cook for another 2 minutes until the sauce starts to thicken.

Check the seasoning. Add pepper to taste. Then scoop the mussels onto warm plates. Drizzle with the rest of the blue cheese sauce and vegetables. Sprinkle with freshly chopped parsley. Serve immediately.