Build the Filling:
Add minced garlic and thyme to the pan. Stir constantly so the garlic turns fragrant but does not burn about two minutes. Dab in the extra butter and once melted sprinkle over the flour. Stir until the flour disappears and thickens around everything. Pour in beef broth in a slow stream stirring as you go. Let this mixture puff and simmer until it is thickened like onion gravy about five minutes.
Stuff and Bake:
Preheat your oven to a hot four twenty five. Nestle the onion bowls into a snug baking dish so they do not topple. Fill each with as much of the savory filling as possible. Slide the dish into the oven and bake for thirty minutes until the onions are melting and starting to color at the edges.
Prepare the Croutons:
As the onions bake cube your sourdough and spread out on a baking sheet. Toast in the oven about fifteen minutes until golden and crispy on the outside.
Finish with Cheese:
After initial baking scatter a little Gruyere inside each onion then pile the toasted bread cubes on top. Heap on more cheese to cover the bread fully. Switch your oven to broil and carefully watch as the cheese bubbles and browns in spots five minutes or less.
Rest and Serve:
Let the onions cool a few minutes before you try to serve. The filling will set a bit and flavors will mingle.
A close up of a French onion stuffed with cheese.
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A close up of a French onion stuffed with cheese. | lilicooks.com
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You Must Know
Loaded with rich caramelized flavor and gooey cheese in every bite
Impressive enough for guests yet can be prepped ahead for weeknights
Naturally vegetarian if you swap the broth for vegetable stock
I never get tired of the deep jammy taste of the onions especially when paired with bubbling Gruyere. My kids love to help toast the bread and sprinkle the cheese for the final crowning glory.
Storage Tips
Leftover stuffed onions can be kept in the fridge for up to four days. I like to reheat them in a covered baking dish at three fifty until hot through so the cheese melts again but the onion shells do not get mushy. They freeze best before adding the bread and cheese topping so you can finish them fresh when ready to enjoy.
Ingredient Substitutions
Swap beef broth for good quality vegetable broth to make the dish vegetarian. If you like a sharper flavor try Swiss or Comte cheese or use a mix. Gluten free flour and bread can be used with similar results. Red onions will be a little softer and sweeter after baking if you want to experiment.
A close up of a French onion stuffed with cheese.
Save
A close up of a French onion stuffed with cheese. | lilicooks.com
Serving Suggestions
Serve these as a showstopping starter for French inspired meals. They also work beautifully with a simple green salad for brunch or pair up with steak or roast chicken for a hearty supper. A big spoonful of seasoned rice or herby mashed potatoes on the side turns a single onion into a full meal.
