Preheat the oven to 300 degrees F. Line a baking sheet with foil.
Combine the halved cherry tomatoes, olive oil, and salt and pepper on the prepared baking sheet. Roast for 1 hour, checking after 30 and 45 minutes, to ensure that they aren't burning. Set aside to cool once done.
Cut the kernels off of the 4 corn cobs.
Blend ~1 cup of the kernels in a blender or food processor with 2-4 tbs of broth. Use just enough broth to make a mostly smooth puree. Set the pureed corn and other kernels aside for a few minutes.
Heat the 5 cups of broth in a medium sauce pan over medium heat. Bring it to a simmer and then turn it to low.
In a heavy-bottomed pan or Dutch oven, heat the olive oil and butter until the butter melts. Add the garlic and remaining corn kernels. Sauté until the garlic is very fragrant.
Add the Arborio rice and stir so that every grain gets coated in the olive oil and butter. Allow the rice to toast a bit, stirring occasionally. Once it starts to smell nutty, add the pureed corn. Stir occasionally until almost all of the puree has been absorbed by the rice.
Turn the heat off under the broth, and add a couple of ladles to the rice. Stir occasionally until, again, almost all of the liquid is absorbed. Repeat this process until the risotto is creamy and the rice is no longer al dente.
Add the Parmesan cheese, stirring until it has been incorporated. Add salt and pepper, to taste.
Top the risotto with roasted cherry tomatoes and fresh basil.