Step 1

Preheat oven to 425°. Poke each squash a few times with a sharp knife, then place on a foil-lined rimmed baking sheet. Roast until a fork easily pierces through skin, about 1 hour. Let sit until cool enough to handle, then cut each squash in half. Scoop out and discard seeds. Tear squash into large pieces and arrange, flesh side up, on same baking sheet.

Step 2

Increase oven temperature to 450°. Bring chiles, maple syrup, vanilla, and a big pinch of salt to a boil in a small saucepan; reduce heat and simmer until thickened, 8–10 minutes. Remove from heat and stir in oil.

Step 3

Generously season squash with salt, then spoon maple syrup mixture over each piece. Roast squash until darkened slightly and jammy in spots, 20–25 minutes.

Step 4

Transfer squash to a platter and sprinkle sesame seeds over.Do ahead: Squash can be roasted 1 day ahead. Let cool. Wrap in foil (leave whole) and chill.