Ingredients

  • 2 cups very thinly sliced onion (about 2 onions)
  • 1 1/2 tablespoons unsalted butter
  • 2 tablespoons water
  • 3/8 teaspoon salt
  • 1/8 teaspoon black pepper
  • 1 (9-inch) refrigerated pie shell (from a 15-ounce package)
  • 3 tablespoons creme fraiche at room temperature
  • 1 1/2 teaspoons finely chopped fresh chives
  • Special equipment: a 2 1/4-inch round cookie cutter; a mini-muffin pan with 12 (1/8-cup) muffin cups

Method

  • Put oven rack in middle position and preheat oven to 375F.
  • Cook onion, butter, water, salt, and pepper, covered, in a 10-inch heavy skillet over moderately low heat, 10 minutes.
  • Remove lid and cook, stirring frequently, until onion is deep golden brown and very tender, about 25 minutes.
  • While onion cooks, roll out dough to slightly less than 1/8 inch thick.
  • Cut out 12 rounds with cutter and lightly press each into a mini-muffin cup.
  • Bake until pale golden, 10 to 12 minutes.
  • Remove tartlet shells from muffin pan.
  • Stir together creme fraiche and chives and divide among shells, then top with caramelized onions.