Heat the ¼ cup of olive oil in a small saucepan over medium heat, just until warm, about 90 seconds. Remove from the heat and stir in the rosemary sprig and garlic cloves. Swirl them in the pan and set it aside to cool and infuse for at least 30 minutes. The longer it rests the more flavor will infuse into the oil.

Preheat the oven to 425 degrees F.

Place the sweet potatoes on a large rimmed sheet pan and drizzle with 1 tablespoon of oil. Stir and spread into a single layer. Bake for 10 minutes.

Add the tomatoes and stir again. Spread into a single layer and bake 15 to 20 minutes until the potatoes are tender and the tomatoes burst. Remove from the oven.

Strain the infused oil into a small dish. Whisk in the salt and pepper. Pour the dressing over the potatoes and tomatoes. Stir well. Serve warm garnished with rosemary leaves.