Ingredients
3 white onions, thinly sliced
extra-virgin olive oil
kosher salt
Black pepper
1 package frozen puff pastry, thawed
1 pre-cooked kielbasa, thinly sliced
grated Swiss cheese
fresh thyme
Preparation
Step 1Preheat oven to 350 degrees. In large skillet, sauté onions in olive oil over medium heat until deeply golden and caramelized, about 20 minutes. Season with salt and pepper. Step 2 Unroll two sheets thawed puff pastry. On floured work surface, roll out puff pastry until slightly thinner. Prick both sheets all over with fork, and transfer to parchment-lined baking sheet. Spread tops with onions, kielbasa, and Swiss, leaving half-inch border around all sides. Bake tarts until puffy and golden, and cheese is melty, about 25 minutes. Step 3Sprinkle with fresh thyme and season with salt and pepper. Slice into squares for serving
