Preheat the oven to 400°F. Lightly coat a large rimmed baking sheet with the olive oil mister or cooking spray.

Spread the squash cubes in a single layer on the baking sheet, spray them lightly with more olive oil, and season with salt and pepper. Roast for about 40 minutes, stirring halfway through, until the squash is fork-tender and browned at the edges.

About 10 minutes before the squash is done, make the brown butter: melt the butter in a small light-colored skillet over medium heat, whisking often. Once melted, add the sage and keep whisking until the butter smells nutty and turns golden brown, 3 to 5 minutes. Remove from the heat right away so it doesn't burn.

Transfer the hot squash to a large bowl, pour the brown butter and sage over it, and toss gently to coat. Taste, adjust the salt and pepper, and serve warm.