Bring a small pot with 1½ cup water and rice to a boil over high heat. Reduce to a simmer, cover, and cook until tender, 18-20 minutes. While rice cooks, prepare ingredients.
Prepare the Ingredients
Trim and thinly slice green onions on an angle. Mince garlic. Pat shrimp dry, and season with half the Cajun seasoning (reserve remaining for sauce).
Make the Biscuis
Measure ⅓ cup water. Place biscuit mix, half the water, half the green onions (reserve remaining for garnish), and cheddar cheese in a mixing bowl. Add remaining water 1 Tbsp. at a time and mix until a sticky dough forms. Wet your hands with water, divide dough into four equal balls, and transfer dough balls to prepared baking sheet. Brush each ball lightly with olive oil. Bake until golden brown, 15-18 minutes. While biscuits bake, sear shrimp.
Sear the Shrimp
Place a large non-stick pan over medium-high heat. Add 1 tsp. olive oil and shrimp to very hot pan. Cook until browned, 2 minutes per side. Transfer to a plate. Shrimp will finish cooking in a later step. Reserve pan; no need to wipe clean.
Make Sauce and Finish Shrimp
Return pan used to sear shrimp to medium-high heat. Add garlic. Cook until aromatic, 30 seconds. Add ½ cup water, cream, tomato paste, and remaining Cajun seasoning (to taste). Cook until thickened, 1-2 minutes. Return shrimp to pan and cook until shrimp reaches a minimum internal temperature of 145 degrees, 1-2 minutes.
Finish the Dish
Place a portion of rice in the middle of a plate. Place shrimp and sauce around rice. Garnish with remaining green onions and serve biscuits on the side.