For the pesto:
4 cups fresh basil
2 garlic cloves, whole
3/4 cup grated parmesan cheese
3/4 cup olive oil
1/2 cup pine nuts
1/2 cup heavy cream
1/4 cold tap water
Kosher salt and fresh ground black pepper
For the pasta:
12 oz. penne pasta cooked very al dente
1 cup halved cherry tomatoes
1 cup shredded parmesan cheese
8 oz. mozzarella cheese (shredded or mini balls)
Heat the oven to 400 F.
Add the basil, garlic, parmesan cheese, pine nuts, heavy cream, and water to a food processor.
Pulse the processor to start breaking down the ingredients.
Add the olive oil to the processor, and blend until the pesto is smooth. Taste and adjust seasoning with salt and pepper.
Add the halved cherry tomatoes and the pesto sauce to the cooked pasta in a bowl. Stir to combine well.
Transfer the pasta mixture to a large, ungreased baking dish. Make sure it is spread evenly.
Evenly sprinkle the top of the casserole with shredded parmesan and mozzarella cheeses.
Place the baking dish in the oven, and allow to cook until the dish is heated all the way through and the cheese is melted.
Remove the casserole from the oven, and allow it to cool for 5 minutes.
Serve while still hot. Garnish with more parmesan cheese, fresh chopped basil or fresh parsley (optional).