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Caramelized Onion Potato Thyme Slab Pie

caramelized onion potato thyme slab pie - featured image
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A golden, flaky slab pie filled with sweet caramelized onions, creamy potatoes, Gruyère cheese, and fresh thyme, all baked in buttery puff pastry. This easy, crowd-pleasing vegetarian dinner is perfect for brunch, potlucks, or cozy nights in.

Ingredients

Scale
  • 2 sheets puff pastry, thawed
  • 2 large yellow onions, thinly sliced
  • 2 medium Yukon Gold potatoes (about 14 oz), peeled and sliced paper-thin
  • 2 tablespoons fresh thyme leaves (or 2 teaspoons dried thyme)
  • 1 cup (about 3.5 oz) Gruyère cheese, shredded
  • 2 tablespoons olive oil
  • 2 tablespoons unsalted butter
  • 2 tablespoons heavy cream
  • 1 large egg, beaten
  • Kosher salt, to taste
  • Freshly ground black pepper, to taste
  • Optional: 2 tablespoons chives, finely chopped
  • Optional: 1/4 cup (1 oz) crumbled goat cheese
  • Optional: 1/2 teaspoon smoked paprika

Instructions

  1. Preheat oven to 400°F (200°C). Line a rimmed baking sheet (about 13×9 inches) with parchment paper. Thaw puff pastry according to package directions.
  2. Heat olive oil and butter in a large skillet over medium-low heat. Add sliced onions and a pinch of salt. Cook, stirring every few minutes, until onions are deep golden and jammy, about 25-30 minutes. Add a splash of water if onions start to stick.
  3. While onions cook, peel and slice potatoes as thinly as possible (about 1/8 inch thick). Toss in a large bowl with heavy cream, salt, and pepper until evenly coated.
  4. On a lightly floured surface, gently roll the two puff pastry sheets together to fit your baking sheet (about 1/4 inch thick). Transfer to the parchment-lined sheet.
  5. Spread caramelized onions evenly over the pastry, leaving a 1-inch border. Arrange potato slices over onions, overlapping slightly. Sprinkle with shredded Gruyère and scatter thyme leaves on top.
  6. Fold pastry edges up and over the filling, pinching corners to seal. Brush exposed pastry with beaten egg.
  7. Bake for 25-30 minutes, or until pastry is deeply golden and crisp and potatoes are fork-tender. Rotate pan halfway through for even browning.
  8. Let pie cool for 5-10 minutes. Garnish with extra thyme or chives if desired. Slice into squares and serve warm or at room temperature.

Notes

For best results, slice potatoes as thinly as possible. Keep puff pastry cold before baking for maximum flakiness. If edges brown too quickly, cover with foil. Variations include swapping in different cheeses or herbs, or making it vegan or gluten-free with appropriate substitutions. Pie can be made ahead, stored in the fridge for up to 3 days, or frozen for up to 1 month.

Nutrition

Keywords: caramelized onion, potato, thyme, slab pie, puff pastry, vegetarian, savory pie, brunch, easy dinner, French tart

Find it online: https://tastypierecipes.com/caramelized-onion-potato-thyme-slab-pie-recipe-easy-puff-pastry-dinner/