In a large saucepan, melt the 2 tablespoons of unsalted butter over medium heat. Once melted, add the 1/2 cup of finely chopped onion and sauté for about 3-4 minutes, or until the onion becomes translucent. Stir in the 3 cloves of minced garlic, 1 teaspoon of kosher salt, and 1/2 teaspoon of freshly ground black pepper, cooking for an additional minute until fragrant.
Add the 1 1/2 cups of long-grain white rice to the saucepan, stirring well to coat the rice in the buttery mixture. Toast the rice for about 2-3 minutes, allowing it to absorb the flavors and become slightly golden.
Pour in the 3 cups of low-sodium chicken broth (or vegetable broth if you prefer). Stir to combine, then increase the heat to bring the broth to a gentle boil.
Once boiling, reduce the heat to low and cover the saucepan with a lid. Allow the rice to simmer for 18-20 minutes, or until all the liquid has been absorbed and the rice is tender.
After the cooking time is up, remove the saucepan from heat and let it sit, covered, for an additional 5 minutes. Then, uncover and fluff the rice gently with a fork. Stir in the 1/4 cup of fresh chopped parsley for a burst of color and flavor before serving.