Step 1

Heat a large Dutch oven on medium heat. Add the butter and melt. Add the onion and fennel,and toss with the butter. Season with a generous pinch of kosher salt, and cook until softened, about 5 to 7 minutes. Add the sage, thyme and garlic. Cook for another 1 to 2 minutes, until fragrant.

Step 2

Sprinkle the flour over the vegetables and cook, stirring constantly, until the flour combines with the butter and forms a wet sand consistency (about 30 seconds to 1 minute). Let it toast for a minute until slightly nutty in aroma and golden in color.

Step 3

Pour the white wine into the pot. Stir constantly and cook for about 1 minute, allowing the alcohol to burn off. Next, slowly pour the vegetable stock into the pot, while whisking. Add the vegetable stock paste and mix into the filling. Once combined, pour the whole milk in and whisk until combined. Season with a generous pinch of kosher salt and pepper and taste to ensure the seasoning is good for you before moving on to the next step.

Step 4

Add the butternut squash, broccoli, carrots, peas and green beans to the filling and stir until combined. Cook, stirring occasionally, until warmed throughout (about 10 to 15 minutes, since we're using frozen vegetables). Once cooked throughout, remove from the heat.

Step 5

Transfer the filling to a fridge-safe dish. Allow it to come to room temperature, then cover with an airtight lid or plastic wrap and place in the coolest part of your fridge for up to 3 days.

Step 6

Thaw puff pastry in the fridge the night before making the potpies.

Step 7

Preheat the oven to 400 F (or according to puff pastry instructions). Place a rack into the center of the oven.

Step 8

Using a ladle or large spoon, generously scoop the filling into ramekins, cocottes or mini cast-iron skillets. The dishes should be slightly overfilled, with the filling sitting about 1/4- to 1/2-inch above the edge of the dish. If making a large casserole style potpie, transfer the filling to a 9- by 13-inch baking dish.

Step 9

If needed, roll out the puff pastry on a lightly floured surface. Slice into large squares and drape each square over the pie filling. Trim any excess edges. If making a casserole-style potpie, roll the puff pastry into one large rectangle and place over your filling, leaving about 1 to 2 inches to drape over the edges on each side. Using a sharp paring knife, create slits in the top of the potpie for ventilation.

Step 10

Brush with egg wash and top with a generous sprinkle of flaky sea salt.

Step 11

Bake for 20 to 25 minutes (or according to puff pastry instructions), until golden-brown and until the filling is bubbling. Remove from the oven and allow them to sit at room temperature for 10 to 15 minutes before serving.