Caramelized Onion and Poppy Seed Hamantaschen

Preparation

1. Step 1

   Mix the flour, sugar, baking powder and 1 teaspoon salt in the bowl of a food processor. Add 9 tablespoons butter and pulse until coarse crumbs form. Add ½ teaspoon balsamic vinegar and the egg yolk and pulse, adding 2 to 3 tablespoons or so of ice water if needed to form a soft dough. Wrap the dough in waxed paper or plastic wrap and refrigerate, about 30 minutes.

2. Step 2

   Meanwhile, heat the oil and the remaining 1 tablespoon butter in a medium nonstick pan over medium-low. Add the onion, thyme, bay leaf and honey, season with salt and pepper and cook, stirring occasionally, until caramelized, about 20 minutes. Discard the thyme sprigs and bay leaf. Stir in the poppy seeds and the remaining 1 teaspoon balsamic vinegar and season to taste. Let cool.

3. Step 3

   Remove the dough from the fridge, heat the oven to 375 degrees and cover 2 large baking sheets with parchment paper.

4. Step 4

   Roll out the dough onto a floured surface until ⅛ inch thick. Using a 2½-inch round mold or glass, cut the dough into rounds. Top each round with a hefty pinch of cheese in the center, then a heaping teaspoon of the cooled onion mixture. Working with one round at a time, dip a pastry brush or your finger into the egg white and moisten the edges of the excess dough surrounding the filling. Fold up 3 sides of the round to form a triangle, partly covering the filling with the dough, and pinch the dough firmly at all 3 tips of the triangle. Transfer to the parchment-lined baking sheets and repeat to make about 36 hamantaschen.

5. Step 5

   Bake until golden, rotating midway through baking, 15 to 20 minutes, then serve warm.