You’ll Need
350ml (1 can) Beer, (Sweet like a Weissbier or malty and rich like a brown Ale, do not use an IPA!)
4 tbsp Butter
4 tbsp Flour
113g Fontina or Gruyere, shredded
1 tbsp Cornflour (Corn-starch)
350ml Milk
2 Brown onions, sliced thinly
2 tsp (or to taste) Dijon Mustard
nutmeg, a pinch
sale and pepper to taste
white wine vinegar or lemon juice, a dash
Method
Melt butter in a large saucepan over medium heat. Add flour and whisk continuously until a blond or golden brown.
Add sliced onions and a pinch of salt. Gently cook onions for 30 minutes, until very soft (some caramelization is fine). Add beer and reduce by half, whisking to prevent clumps.
Meanwhile, toss grated cheese with cornflour to evenly coat. Slowly whisk milk into the sauce mixture and bring to a simmer. Slowly incorporate cheese in 3 parts, making sure to bring the mixture back to a simmer after each addition. If the milk has reduced by more than one third, add more to prevent it from becoming too thick. Let the mixture cool down to at least 80°C.
Place all ingredients in a blender and season with mustard, nutmeg, salt, pepper and vinegar. Use a lid and take care to Blitz until smooth. Adjust seasoning to your taste.
To Serve
Reheat in a microwave safe bowl or in a saucepan over low heat, stirring continuously to prevent sticking on the bottom.