Preheat your oven to 375°F (190°C). Lightly grease a baking dish.

Cook the penne pasta in salted boiling water until al dente, then drain, reserving ½ cup of starchy water.

Toss chopped kale with olive oil, salt, and pepper. Spread on a baking sheet and roast for about 10 minutes until tender.

In a large bowl, mix cooked pasta, roasted kale, pesto sauce, and reserved starchy water until well combined.

Transfer to the baking dish and top with mozzarella cheese.

Bake for 20-25 minutes until bubbly and golden brown. Serve hot with extra pesto if desired.