Cook the Pasta: Bring a large pot of salted water to a boil. Add the brown rice pasta and cook according to the package instructions, usually 7-9 minutes, until tender. Drain and set aside.
Prepare the Vegetables: While the pasta is cooking, heat olive oil in a large pan over medium heat. Add the onion and garlic, cooking for 2-3 minutes until softened and fragrant.
Add the Tomatoes and Spinach: Stir in the halved cherry tomatoes and cook for another 2-3 minutes until they start to soften. Add the spinach leaves and cook for 1 more minute until wilted.
Combine the Pasta and Vegetables: Add the cooked brown rice pasta to the pan with the vegetables. Toss everything together and season with salt and pepper to taste.
Serve: Plate the pasta, and top with grated Parmesan cheese and fresh basil leaves for garnish, if desired. Serve immediately.