Gratiné d'oignons - Testing

https://www.delish.com/cooking/recipe-ideas/a28691583/french-onion-mac-and-cheese-recipe/?utm_campaign=socialflowFBDEL&utm_source=facebook&utm_medium=social-media&fbclid=IwAR1Ha2Qpv-j_yM-B_NfCKX8-jcJw-4bffXH54kFt7wqC0u-Kii8jkqbSuAk

1 - Really good. I didn't have the exact ratios of cheeses but it worked out really nicely. It's another Macaroni and Cheese but this version re-heats really well. There is much more goo than my usual recipe. I think I can probably play with cheeses. I have nothing against Fontina, but it isn't a usual cheese for me and I do like to keep things simple and trim.

5 tbsp. (70g) butter, divided, plus more room temperature for brushing
2 large (20oz/570gr) yellow onions, thinly sliced
Kosher salt
8 oz. cavatappi or other short curly pasta
2 tbsp. all-purpose flour
2 1/2 c. whole milk
Cheese (total 18oz/517g) 

- 1 c. (4 oz/115g) grated fontina cheese (or Gruyère)
- 2 1/2 c. (10 oz/287g) grated Gruyère
- 1 c. (4 oz/115g) shredded sharp white cheddar
1 tsp. Dijon mustard
Pinch of cayenne pepper
1 tsp. fresh thyme leaves, plus more for garnish

1/2 tsp salt

1/4 tsp pepper

1. In a large skillet, melt 3 Tbsps. (42gr) of the butter and cook the onions with a pinch of salt, stirring occasionally, until they are golden, about 30 minutes. Set aside.
2. Preheat oven to 350°F. 
3. Cook pasta in a large pot of boiling salted water until just al dente. Drain pasta.
4. In the empty onion pan, melt the remaining 2 Tbsps. (28g) butter. 
5. Blend in the flour and cook, stirring, 1 minute or until just starting to colour.
6. Stir in the milk and whisk while it simmers until it thickens into a sauce.  
7. Holding back 1 cup of the gruyere, stir in all the cheese and stir until it's melted. Remove from the heat. 
8. Stir in the cooked pasta, caramelized onions, Dijon, thyme, and cayenne. Season with salt and pepper.
9. Put in a gratin dish or in individual ramekins and bake until sauce is bubbly around the edges, about 20 minutes. 
10. Switch the oven to broil and broil until cheese is golden, about 2 minutes. Garnish with more thyme before serving.