Peel and seed the butternut squash. Grate half of the squash using a box grater. Cut the other half of the squash into small cubes.
Heat oil in a large nonstick skillet over medium-low heat. Add onion and garlic and cook 10 minutes, until soft and lightly browned.
Combine water and tomato paste and stir into the pan. Add rice and stir to coat.
Add the squash and stir until it has reduced enough to cover the pan.
Increase the heat to medium-high, pour in 2 cups broth, and bring to a boil.
Reduce the heat to medium-low, cover, and cook stirring occassionally, until the rice has absorbed most of the liquid and the squash and rice are tender. Depending on the rice used, this should take 25 to 30 minutes. Add more broth if needed to prevent sticking and ensure rice is cooked.
Stir in herbs, salt, and pepper. Remove from the heat and let stand, covered, for 5 minutes before serving.