French Onion Tart
Quick answer
- Total time
- 55 min
- Level
- Medium
- Servings
- 4 servings
- Ingredients
- 8
About this dish
Three onions cooked slowly in butter for more than 20 minutes, until deep amber, are nearly the whole tart.
Read more
There is only enough egg and cream custard to hold them together, and Gruyere on top bakes into a salty brown crust.
Ingredients
Instructions
- 1
Slice 3 onions lengthwise into thin 2mm pieces.
Keep the thickness even from end to end, because uneven slices will brown at different speeds and some pieces may burn before the rest become sweet.
- 2
Melt 2 tablespoons butter in a heavy pan, then add the onions.
Cook over low heat for 20-25 minutes, stirring now and then, until the onions collapse into a deep amber layer with no sharp raw smell.
- 3
Roll 250g tart dough to 3mm thickness and press it firmly into the tart pan base and sides.
Trim the edge, prick the bottom with a fork, and chill for 20 minutes so it shrinks less.
- 4
Bake the chilled empty shell at 190C for 10-12 minutes first.
Remove it when the surface looks dry and the edges have just started to color, which helps the base stay crisp under the custard.
- 5
Whisk 1 egg, 80ml heavy cream, 0.5 teaspoon salt, and 1 teaspoon thyme in a bowl.
Mix until smooth with no visible streaks, remembering that the Gruyere will add more saltiness during baking.
- 6
Spread the onions in the baked shell and pour in the custard slowly so it settles between them.
Scatter 120g grated Gruyere on top, bake at 190C for 25-30 minutes, then rest 10 minutes before slicing.
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