Preheat the oven 400˚F.
Combine the tomatoes, shallots, garlic, thyme, salt and pepper in a large roasting tin. Drizzle the olive oil on top and toss to coat all vegetables in the oil. Roast in the oven for 30 minutes.
Once finished roasting, transfer the contents to a large stockpot. Remove the thyme sprigs. Add the stock and bring to a gentle simmer. Continue to simmer for 10 minutes. Stir in the BBQ sauce. Simmer for an additional 5 minutes. Using a stand or hand blender, blitz until you have a smooth and creamy consistency. Taste the soup for seasoning and adjust with more salt and/or pepper as you like.
Optional: If topping the soup with puff pastry, fill your soup bowls with the soup and set aside to cool slightly. Cut out circles of puff pastry a 1/2-inch wider in diameter than your soup bowl. Brush each circle with the egg yolk and score the surface using the tip of a sharp knife, taking care not to cut through the pastry. Brush the rim of your soup bowl with the egg yolk and place the circle of puff pastry on top, pressing the edges so they firmly stick to the top of bowl. Repeat for all soup bowls.
Place the prepared soup bowls on a rimmed baking tray and return to the oven for 10-15 minutes to cook the puff pastry through. You should have a nice golden brown color on your puff pastry. Enjoy while warm.