Heat a drizzle of oil in a large pan over medium-high heat. Add the mushrooms and cook, stirring occasionally, until browned, 5-8 minutes. Transfer the mushrooms to a plate.
If the pan seems dry, add another drizzle of oil. Add the chicken and cook, breaking up into pieces, until browned and cooked through, about 5-8 minutes. Add the chili sauce and soy sauce and cook, stirring, until thoroughly combined, 2-3 minutes more.
Add the chicken to one side of a large serving platter. To the other side of the platter, add the mushrooms, water chestnuts, carrots, cabbage, and noodles in separate sections (it’s ok if they mingle a little!).
Add the butter lettuce to the edge of the platter around the chicken filling and serve!