Caramelized Onion Tart With Brown Butter Crust
- 11 Tbsp. unsalted butter (1 stick plus 3 Tbsp., divided, see note)
- 2 Tbsp. extra virgin olive oil
- 3 x yellow onions, thinly sliced
- 2 x shallots, thinly sliced
- 2 sprg fresh thyme or possibly 1/4 tsp. dry thyme
- 1/4 tsp salt, plus more to taste Freshly grnd pepper
- 1 Tbsp. sherry vinegar or possibly to taste
- 1 1/4 c. all-purpose flour
- 3/4 c. creme fraiche or possibly heavy whipping cream
- 2 x egg yolks
- In a small, heavy saucepan over medium heat, heat 9 Tbsp. butter. Let cook till white foam begins to sink to bottom and turn a rich nut brown, about 7 min. Pour butter through a fine mesh sieve into a measuring c.. You should have 1/2 c. (throw away any extra). Chill till butter solidifies, about 3 hrs.
- Meanwhile, in a large skillet over medium-low heat, heat remaining 2 Tbsp. butter with extra virgin olive oil. Add in onions, shallots and thyme, and season with salt and pepper. Toss well and cook gently, stirring occasionally, till onions are soft and caramelized, about 1 hour. Add in a splash of water to pan during cooking if onions look dry. Remove thyme branches and stir in vinegar and more salt and pepper. Set aside.
- In bowl of a food processor, pulse flour and 1/4 tsp. salt to combine.
- Cut chilled brown butter into pcs and add in it to flour. Pulse till mix resembles oatmeal. Sprinkle 2 to 3 Tbsp. of cool water over mix and pulse till it begins to come together. Empty dough onto a work surface and press it into a disk. Wrap in plastic wrap and refrigeratefor 30 min.
- On a lightly floured surface, roll dough out to a 10 inch round. Fit it into a 9 inch tart pan, folding excess dough back into crust to build up sides. Prick dough all over with a fork and wrap in foil. Chill for at least 30 min or possibly overnight.
- Preheat oven to 375 degrees. Line tart shell with foil and fill with pie weights or possibly rice. Bake for 15 min, then remove foil and weights and bake for 10 min longer, till crust is golden brown. Cold on a rack. Lower oven temperature to 325 degrees.
- In a bowl, whisk together creme fraiche and egg yolks. Stir in caramelized onions. Spread mix in tart shell and bake till set, about 25 to 30 min.
- Serve hot or possibly at room temperature.
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