Combine the diced tomatoes, garlic, and basil in a bowl. Toss with olive oil and season with salt and pepper. Refrigerate for at least one hour.
Combine the risotto with a splash of milk and season with salt and pepper. Push a small layer of risotto into the bottom of individual springform pans. Top with the tomato mixture, another layer of risotto, and finish with a layer of tomatoes.
Refrigerate for 12 hours, or overnight. Garnish with fresh basil before serving.