Combine the peanut butter, chili garlic sauce, soy sauce, and brown sugar in a bowl until it forms a smooth paste.
Bring a small pot of water to a boil over high heat. Once boiling, take ¼ cup of the water and stir it into the peanut-chili paste until it forms a smooth, pourable sauce.
Add the ramen noodles (without seasoning packet) to the boiling water and boil for 2-3 minutes, or just until the noodles are tender.
Drain the noodles, then return them to the pot with the heat turned off. Pour the peanut sauce over top and stir to combine. Top with sliced green onions and serve immediately.