Preheat oven to 375 degrees F.

In large bowl, toss butternut squash with 2 tablespoons olive oil, thyme, nutmeg, salt and pepper. Arrange on rimmed sheet pan in single layer; bake 25 minutes or until tender.

Meanwhile, in large sauté pan over medium-high heat, combine 1 tablespoon olive oil and butter. Once glistening, cook onions 10 minutes, stirring occasionally.

Reduce heat to medium; continue cooking onions 10 to 15 minutes, until soft and light brown.

In large bowl, use fork to mash roasted butternut squash. Set squash and caramelized onions aside until cool enough to handle.

Reduce oven temperature to 350 degrees F. Line sheet pan with parchment paper.

On lightly floured surface, roll out puff pastry sheets. Cut each into 9 equal squares (18 total). Gently stretch each square to 4”x4”.

In center of each puff pastry square, drop 1-1/2 tablespoons butternut squash, 1/2 tablespoon caramelized onion and 1/2 to 1 teaspoon feta cheese.

Brush edges of pastry squares with egg wash; fold to form triangle. Use fork to crimp edges.

On prepared sheet pan, arrange turnovers 1/2" apart. Brush top of pastries with remaining egg wash. Bake 20 to 25 minutes, until golden brown. Serve warm.