In a pan over medium-low heat, heat the grapeseed oil. Add the onions and garlic and caramelize until golden brown, approximately 10 minutes. Deglaze with the beer and let it cook out for 3 to 4 minutes. Add the beef stock, thyme and bay leaf, then bring to a boil. Let simmer for 10 more minutes. Add the butter and slowly incorporate it into the broth so it thickens the broth lightly, about 2 minutes. Season with salt and pepper.
Preheat the broiler.
Fill a small ovensafe bowl with the onion mixture and cover with the Cheddar and Swiss. Melt the top under the broiler until golden, 1 to 2 minutes (or with a kitchen blowtorch). Serve with the toasted baguette.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.
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