Preheat grill to medium-high.
To wash mushrooms: dampen a paper towl and gently rub outside of mushrooms to clean. Do not immerse in water.
Brush mushrooms with 1 tbsp olive oil and season with 1/4 tsp salt and 1/4 tsp pepper. Grill, gill side up for 5 minutes. Flip and continue grilling until tender, about 5 more minutes.
Meanwhile, in a small bowl, mix pesto, ricotta cheese, parmesan, 2 tbsp fresh basil and salt and pepper to taste.
Flip the mushrooms back to gill side up and stuff them with ricotta mixture.
Grill additional 5 minutes or until filling is hot.
While mushrooms are finishing up, combine salad ingredients.
Serve mushrooms with side salad. Garnish with remaining fresh basil and extra drizzle of olive oil.