Heat oven to 425º F. Cook the pasta according to the package directions. Drain and let cool.
Arrange the tomatoes in a single layer on a baking sheet. Drizzle with the oil. Season with ½ teaspoon salt and ¼ teaspoon pepper. Scatter the thyme on top.
Place the tomatoes in the oven and bake until soft, 15 to 20 minutes. Set aside to cool.
Divide the pasta among 6 large bowls. Spoon some of the ricotta over each serving. Top with some of the tomatoes and thyme sprigs.
Drizzle with the oil and sprinkle with the lemon zest and pepper to taste just before serving.