Cut the squash in half lengthwise, scoop out seeds and fibers.

Place the squash halves in a microwave-safe dish and cover. Microwave for 8 to 9 minutes.

Remove from microwave and scoop out the flesh with a fork into a large bowl.

Meanwhile, in a small blender, combine basil, garlic, olive oil, parmesan cheese, salt, and pepper. Puree until smooth.

Combine pesto with two cups of the spaghetti squash (reserve remaining squash for another recipe).

Add diced tomatoes to the mixture and season with additional salt and pepper as needed.