Preheat oven to 400 degrees F. Line baking sheet with parchment paper or silicone baking mat.

Place cubed butternut squash on sheet pan, drizzle with olive oil and toss with rosemary, salt, nutmeg and black pepper. Spread squash evenly in one layer on pan. Roast for 30 minutes, turning halfway, or until squash is lightly golden and tender. Remove from oven and set aside. Lower oven temperature to 375 degrees F.

In large skillet, heat olive oil over medium-high. Add leeks and fennel and sauté for 6 minutes, or until fragrant and tender. Add garlic, kale, tamari, apple cider vinegar, salt and black pepper and sauté for 4 additional minutes. Add cooked butternut squash, cannellini beans, vegetable stock, flour and rosemary. Cook 3 to 4 more minutes, stirring occasionally. Remove from heat and transfer mixture to shallow 2-quart baking dish.

On lightly floured surface, gently roll out puff pastry to smooth any creases and flatten sheet. Drape over baking dish; leaving corners of the pastry hanging over slightly. Brush pastry surface with olive oil and sprinkle with flaky sea salt and fresh rosemary, if desired.

Use paring knife to make four thin slits near the center of the pastry. Bake for approximately 40 minutes, or until pastry is golden brown. Let sit for 10 minutes before serving.