2 lb. medium carrots, tops trimmed to about ½", scrubbed
6 Tbsp. unsalted butter, cut into pieces
⅓ cup (packed) light brown sugar
⅓ cup pure maple syrup
¾ tsp. crushed red pepper flakes
Flaky sea salt (optional)
Preheat oven to 400°. Line a rimmed baking sheet with 3 sheets of foil (you’ll need it!). Cut carrots on a diagonal into 3" pieces (halved or quartered lengthwise if large).
Spread out carrots on foil. Evenly top with butter, brown sugar, syrup, and red pepper flakes. Season with kosher salt and toss to combine.
Bake carrots, tossing every 20 minutes, until tender and browned around the edges, 50–60 minutes. Transfer to a platter (with syrup, if desired). Sprinkle with sea salt (if using).