In a large pot, heat the vegetable oil over medium-high heat. Add the chicken pieces, seasoning them with salt, pepper, garlic powder, and ginger. Cook until the chicken is browned and cooked through, about 5-7 minutes.
Pour in the chicken broth, soy sauce, sriracha, and sesame oil. Bring to a boil, then reduce the heat and let it simmer for 10 minutes.
Add the ramen noodles, baby spinach, and sliced mushrooms to the pot. Cook according to the noodle package instructions, usually about 3-4 minutes, until the noodles are tender.
In a small bowl, whisk together the heavy cream and lemon juice. Stir this mixture into the pot and cook for an additional 2 minutes until heated through.
Serve the ramen hot, garnished with chopped green onions and fresh cilantro.