Mix the butter and orange zest until well incorporated. Refrigerate while the carrots are roasting.
Arrange the orange slices on the bottom of an oiled shallow baking dish and cover with a few thyme sprigs.
Toss the carrots ( scrubbed well and dry ) with the olive oil and a pinch of sea salt and place them on top of the oranges and thyme.
Roast at 425″ for about 40 minutes, until al dente turning once half way through cooking. If you prefer them softer cook an additional 10 minutes.
Remove the carrots from the oven and top with thin small dabs of the cold orange butter. Sprinkle with some fresh herbs and enjoy as a side dish next to steaks, roasts or chicken.
If you prefer a deeper caramelization of the carrots, just throw them under the broiler fire for a minute or two.