While the rice is cooking, heat the barbecue grill on medium heat.
In a medium size bowl add the raw shrimp, chili powder, granulated garlic, pepper, salt and olive oil.
Mix the shrimp with the spices and olive oil until the shrimp are completely coated. Set aside.
Lay the shrimp on a preheated grill and cook on both sides until done (about 3 to 4 minutes per side for large shrimp).
Remove the shrimp from the grill and set aside for just a moment while browning the butter.
For the Browned Butter - heat a small skillet on low heat and add butter. Stir as the butter melts. Continue stirring.
When the butter turns a golden color remove the skillet from the heat. At about this time the rice should be done.
Add half of the browned butter to the mushrooms and rice. Gently mix together.
Add the mushrooms and rice to a serving dish (or individual serving dishes).
Top with the shrimp. Drizzle the remaining browned butter over the shrimp and rice.
Sprinkle chopped green onion on top of the dish and serve while warm.