Preheat the oven to 400°F. Add the remaining 2 tablespoons butter and the sea salt to the skillet with the butter used to fry the sage and heat over medium-high heat until the butter is melted. Add the squash, toss quickly to coat, and cook, tossing once or twice, until the squash is lightly browned on at least one side, 8 to 10 minutes. Transfer the squash to a baking sheet, arranging it in one well-spaced layer. Roast until the squash is crispy and firm outside and soft on the inside, 20 to 25 minutes.