Heat a large skillet over medium-high heat adding butter to melt.
Add onions and cook about 10 minutes, stirring frequently, until softened.
Slowly add pineapple juice, a little at a time, letting everything cook into the onions.
Cook until onions are caramelized to your liking and the pineapple juice has evaporated. Remove from the heat.
Preheat oven to 350°F.
Roll out puff pastry sheets and cut each sheet into 9 squares (18 squares total). Place squares on a piece of wax paper or parchment paper (this will prevent sticking).
Brush Hot Pepper Berry Bacon Jam onto each square of puff pastry.
Divide onion mixture amongst the 18 squares.
Top with ham and swiss cheese. Don't overfill, otherwise it will be very difficult to seal the edges.
Brush egg wash around the perimeter of each pastry square. Carefully fold dough over filling to create triangles. Pinch edges closed to create a good seal. Generously brush top of each turnover with egg wash.
- Place on a parchment paper lined baking sheet.
- Note: at this point you can freeze them to bake and serve later. Or bake and serve immediately.
Bake 15 to 20 minutes or until lightly golden.
Serve immediately with a sprinkle of chopped fresh thyme and flaky sea salt.