Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.

In a large mixing bowl, toss together the diced butternut squash, carrots, parsnips, sweet potatoes, and Brussels sprouts. Drizzle olive oil over the vegetables, then season with salt, pepper, fresh thyme, and rosemary.

Spread the vegetable mixture evenly on the prepared baking sheet and roast for 25-30 minutes, stirring midway through roasting.

While the vegetables are roasting, melt butter in a large skillet over medium heat. Add chopped onions and minced garlic, sauté until translucent and fragrant, about 3-5 minutes.

Sprinkle all-purpose flour into the skillet, stirring continuously for 1-2 minutes to form a roux.

Slowly whisk in the vegetable broth until well combined. Allow it to simmer for 3-4 minutes until thickened.

Remove the roasted vegetables from the oven and fold them into the skillet with the sauce. Stir in heavy cream, and adjust seasoning as desired.

On a lightly floured surface, roll out the thawed puff pastry and use a round cutter to create circles larger than your ramekins.

Spoon the creamy filling into your prepared ramekins, filling just below the rim. Drape the pastry circles over the bowls, pressing edges to seal.

Apply an egg wash over the pastry tops and bake for 20-25 minutes, until the crust is puffed and golden brown.

Allow the pot pies to cool for 5-10 minutes before serving.