In a pot, cook the pasta in salted water according to the directions on the package.
In another pot, prepare the shrimp stock by pouring in the chicken stock and simmering with the shrimp shells for a few minutes. Remove the shells by straining and set aside.
Cut the white part of the lemongrass into thin, circular pieces. Mince the thai chilis and garlic. Use a mortar and pestle to crush the chili, garlic, and lemongrass mixture. If you don’t have a mortar and pestle, mincing the ingredients should do the trick too, but it does release the flavor more (and it’s always fun to use).
Saute the lemongrass garlic chili mixture in a skillet with cooking spray. Add in the mushrooms, corn, and onion into the mix.
Once vegetables have softened, add in the shrimp. Cook for about 1-2 minutes each side or until the shrimp begins to curl.
Add in the finished noodles and shrimp stock, and Tom Yum paste block and mix thoroughly.
Remove from heat, garnish with cilantro and cheese, and enjoy!