Preheat the oven to 400 degrees F. Line 2 sheet pans with parchment paper.
On a prepared sheet pan, toss the cherry tomatoes with 1 tablespoon olive oil, 1/2 teaspoon salt and 1/4 teaspoon pepper. Arrange cut-side up in a single layer. On the other sheet pan, toss the potatoes with the remaining olive oil, salt and pepper, and place cut-side down.
Roast for 20-25 minutes until the tomatoes are slightly wrinkled. Continue roasting the potatoes for an additional 20-25 minutes until they are golden brown and tender when pierced with a paring knife.
In a large bowl, toss the potatoes with the pesto, and gently fold in the tomatoes and chives.