Preheat oven to 400 degrees.
Toast sesame seeds in a small skillet over medium-high, shaking pan frequently, until golden brown, 1 to 2 minutes.
Add cumin seeds and toast until fragrant, about 30 seconds more.
Transfer seeds to a small bowl; let cool.
Toss squashes with coriander, 2 teaspoons salt, ¼ teaspoon pepper, and oil on a rimmed baking sheet.
Spread in a single layer; roast 15 minutes.
Add sesame mixture and toss to coat, then flip slices.
Roast until squashes are tender and golden brown, about 15 minutes more; serve.
