Preheat the oven to 400 F
Prepare your vegetables by finely dicing the sweet potatoes, carrots and butternut squash to 1/2" cubes.
Add the butter to a large braiser pan or oven-safe skillet and melt over medium heat. I suggest a pan that’s at least 12-15″ wide and holds at least 3.5 quarts.
Add in the diced onion to the butter and cook for 5-7 minutes, stirring occasionally
Add in the sweet potatoes, butternut squash and carrots and toss together for 3-4 minute.
Mix in the spices with the 2 tbsp olive oil and fresh thyme, then add in the flour and stir together.
Pour in the broth and milk and give everything a mix. Cover the pan and simmer on low for 12-15 minutes. After 15 minutes, taste and adjust salt as needed and remove from flame.
Mix in the white beans and shredded kale then set aside while you prepare the pastry sheet. **If you're preparing this dish ahead of time, you can stop at this step and finish baking with the puff pastry at least 40 minutes before serving. The filling can be prepared and refrigerated up to a day in advance.
Roll out the puff pastry to thin it out so its large enough to fit over the filling. Cover the filling with the rolled out pastry sheet, overlapping the edges into the pan. I like to place a few sprigs of rosemary on top of the pastry
Whisk an egg in a small bowl and brush the top of the puff pastry with the egg. Poke a few holes with a fork throughout the pastry sheet.
Bake for 25-30 minutes, until browned. Let stand for 10 minutes before cutting into it.
Leftovers can be refrigerated for 4 days. To reheat leftovers, place the amount you want to reheat into the oven while you preheat the oven to 350 F. Let it warm while it reheats and then cook for another 5-10 minutes once the oven is warm.