Remove from the heat and let the pears cool in the cooking liquid.. With a slotted spoon, remove the pears from the cooking liquid; set aside on a plate.
Stir in mole and 2 teaspoons kosher salt, and bring to a simmer over medium.Reduce heat to low; partially cover, and simmer, stirring often, until consistency is similar to heavy cream and reduced to about 2 1/2 cups, about 20 minutes.
If mole is too thick, add up to 1/4 cup broth to reach desired consistency.Cover and keep warm over low..While mole simmers, spread squash in an even layer on a large rimmed baking sheet; drizzle evenly with 2 tablespoons oil, and sprinkle evenly with 3/4 teaspoon kosher salt.
Roast in preheated oven until squash is lightly golden on both sides and tender when pierced with a fork, 25 to 30 minutes, flipping once halfway through roasting time.Remove squash from oven, and set aside..
In a small bowl, whisk together buttermilk, vinegar, maple syrup, remaining 1/4 cup oil, and remaining 1/2 teaspoon kosher salt until combined; drizzle evenly over roasted squash on baking sheet.. Pour about 1/3 cup mole on each of 6 plates; top evenly with roasted squash wedges, drizzling any remaining buttermilk mixture from baking sheet over squash.
Sprinkle with flaky sea salt to taste.Reduce heat to medium-low, and simmer, stirring often, until reduced to 1 cup, 25 to 30 minutes.
While cream simmers, melt 2 tablespoons butter in a large skillet over medium-high.Add 1 cup onion and 1 1/2 tablespoons garlic, and cook, stirring often, until onion is translucent and just tender, about 3 minutes.
Carefully transfer hot cream and onion mixture to blender with spinach.Process until bright green and smooth, about 1 minute.