Bring water to a boil in a medium saucepan. Add orzo and 1/4 teaspoon salt and cook until tender, 7 to 10 minutes. Drain and rinse with cold water; set aside.
Meanwhile, bring broth to a simmer in a small saucepan over low heat. Toast kasha in a large skillet over medium-high heat, about 3 minutes.
Reduce heat to low and slowly stir in the hot broth. Add carrots, butter, thyme, pepper and the remaining 1/4 teaspoon salt. Cover and cook until the kasha is tender and all the broth has been absorbed, 10 to 12 minutes. Stir in the reserved orzo, parsley and scallions.
Make Ahead Tip: Cover and refrigerate up to 1 day in advance. Reheat in a shallow, lightly oiled, covered 2-quart baking dish at 400°F for 20 minutes.