Heat the butter in a pot over medium heat. Add the onions and bay leaf and cook, stirring constantly, until the onions become soft and clear, 2-3 minutes.
Add the salt, thyme, and white pepper. Cook, stirring constantly, for 20-30 seconds.
Reduce heat to low and add the rice. Cook, stirring constantly, for 1-2 minutes.
Add the water and bring to a boil. Immediately reduce heat to very low. Cover the pot and cook for exactly 17 minutes. Remove bay leaf, stir, and serve.