Step 1

Preheat a grill for cooking over medium heat. Lightly oil the grill grates.

Step 2

Melt the butter in a small saucepan and turn off the heat. Remove 1/4 cup of the melted butter and reserve. Whisk the maple syrup, cider vinegar, dry mustard, crushed red pepper, 3/4 teaspoon salt and a few grinds of pepper into the saucepan. Bring to a simmer and cook for about 4 minutes to reduce slightly. Remove the glaze from the heat and let cool. Set aside 1/3 cup of the glaze for drizzling at the end.

Step 3

Carefully halve the squashes from the stem to the bottom. Scoop out the seeds with a spoon and discard. Place the squash halves flat-side down and slice crosswise into 1/2-inch scalloped half-moons. Place the slices in a very large bowl.

Step 4

Mix together the chili powder, coriander, cinnamon, 1/2 teaspoon salt and 1/4 teaspoon pepper in a small bowl. Sprinkle the spice mixture over the squash slices. Drizzle the reserved 1/4 cup of melted butter over the squash. Toss with your hands to make sure the slices are evenly coated.

Step 5

Place the squash slices on the grill and cover. Cook until dark grill marks appear, about 10 minutes. Flip the squash slices; cover and cook until the squash is just tender enough to be pierced easily with a paring knife, 7 to 8 minutes more.

Step 6

Brush the squash slices with the glaze and flip. Cook 1 minute, brush with glaze, flip and cook on the other side for another minute. Remove from the grill and arrange on a large platter. Drizzle with the reserved glaze. Sprinkle with the pepitas. Serve warm or at room temperature.