Preheat your oven to 400°F (200°C).

In a large mixing bowl, toss together diced butternut squash, carrots, parsnips, sweet potatoes, and halved brussels sprouts with olive oil, salt, pepper, thyme, and rosemary.

Spread the seasoned vegetable mixture onto a baking sheet in a single layer and roast for 25-30 minutes, stirring halfway through.

Melt butter in a large sauté pan over medium heat. Add chopped onion and minced garlic, and sauté for about 5 minutes until translucent and fragrant.

Whisk in all-purpose flour into the onion and garlic mixture, cooking for 1-2 minutes until it forms a thick roux.

Gradually pour vegetable broth into the roux while whisking continuously. Bring to a simmer and let thicken for about 3-4 minutes.

Once thickened, stir in heavy cream and roasted vegetables, taste and adjust seasoning.

On a lightly floured surface, roll out chilled puff pastry to about ¼ inch thickness. Cut out rounds or squares for the ramekins.

Fill each ramekin with the vegetable filling, leaving room at the top, and place puff pastry over each, sealing edges.

Brush the pastry with a beaten egg and bake for 20-25 minutes until golden brown.

Let the pot pies cool for about 5-10 minutes before serving.