Mince garlic. Cut mushrooms into 1/4" slices. Halve grape tomatoes. Rinse shrimp, pat dry, and season both sides with 1/4 tsp. salt and a pinch of pepper.

Heat 2 tsp. olive oil in a medium non-stick pan over medium heat. Add mushrooms to hot pan and cook 5 minutes, stirring occasionally, or until lightly browned. Add garlic to pan and cook 1 minute, while stirring, or until fragrant. Remove from burner and add grape tomatoes to pan. Stir and season with 1/4 tsp. salt and a pinch of pepper. Remove vegetables to a plate, cover, and set aside. Wipe pan clean.

Once water is boiling, add grits in a steady stream, along with 1/4 tsp. salt, and stir. Reduce heat to low and cook 5-7 minutes, stirring constantly, or until grits are smooth and thickened. Remove from burner and stir in butter and pecorino (reserve a pinch for garnish). Cover and set aside. As cooked grits begin to cool, they may "tighten" up. If this occurs, stir in warm water 1 Tbsp. at a time to return to a smooth, creamy consistency.

Return pan used to cook vegetables to medium-high heat and add 1 tsp. olive oil. Add shrimp to hot pan and cook 2-3 minutes per side, or until shrimp is golden brown and reaches a minimum internal temperature of 145 degrees. Remove pan from burner, add basil pesto (reserve a pinch for garnish), and toss to coat.

Place a serving of grits on a plate or in a bowl. Top grits with cooked vegetables and shrimp. Garnish with remaining pecorino and drizzle with remaining basil pesto.