Preheat oven to 400 degrees. Slice all of the larger carrots in half lengthwise to make them match better with their peers, so that they cook evenly.
Add the carrots to a rimmed baking sheet, then pat off any excess water with a paper towel. Drizzle carrots with olive oil, sprinkle them with thyme & seasoned salt, toss to coat, and spread out in a single layer across the pan.
Roast at 400 degrees for 25-30 minutes or until tender to your liking, stirring halfway through. (I did mine for 25 minutes because I like a little firmness in my roasted veggies; if you like yours more tender, just let them go a little longer.)
Melt the butter right before taking carrots out of the oven. Move the roasted carrots to a bowl, and toss with melted butter to coat.
Note: If you’re making this in the summer with fresh thyme, substitute 1.5 tsp chopped fresh thyme leaves for dried.