Preheat the over to 425 degrees F. Cut the pumpkins in half lengthwise and scrape out the strings and seeds with a spoon. Brush the insides of the pumpkins with 2 tablespoons of the olive oil and place them cut side down on the baking sheet.
halve and core the pears and place them cut side up around the pumpkin halves.
Place the baking sheet in the oven, and remove the pears when soft and lightly browned, about 20minutes. Continue roasting the pumpkin until a fork easily pierces all the way through (about 20 minutes longer).
Scoop the flesh out of the pumpkins and set aside in a bowl.
Heat remaining tablespoon of oil in a large pot or dutch oven, over medium heat. Add the onions and garlic, and cook until softened, stirring occasionally (about 5 minutes).
Add the pumpkin and pears back to the pot, along with the spices, salt and pepper and stock. Bring to a boil and simmer for about 15 minutes.
Remove from heat. Puree the soup with an immersion blender, or in batches in a regular blender and return to the pot. Stir in 1/2 cup of evaporated milk, maple syrup, and vinegar. Taste and adjust the seasoning as necessary. If the soup is too thick, stir in a little more stock or water.
Ladle soup into bowls and garnish with a drizzle of olive oil and some roasted pepitas if desired.