Adjust oven rack to the lowest position and preheat oven to 425°F.
Trim both ends off each delicata squash.
Stand one squash upright on the larger cut side and slice it lengthwise down the center to create two even halves. Repeat with the second squash.
Use a spoon to scrape out and discard the seeds and fibrous flesh.
Place all four squash halves cut-side down on a cutting board. Slice each half crosswise into 1-inch-thick pieces.
Transfer squash slices to a large bowl.
Add melted butter, salt, and black pepper, and toss until evenly coated. (This is a great place to add additional seasonings if desired.)
Arrange squash slices on a rimmed baking sheet, spacing them evenly around the perimeter.
Roast until the bottoms are golden brown, about 12 minutes.
Flip each slice using tongs and return to the oven.
Continue roasting until the second side is golden and tender, about 10 more minutes.
Remove from the oven, transfer to a serving platter, and serve warm.