Preheat oven to 375°F. Spread hazelnuts on a small baking sheet and toast for 5-6 minutes, until lightly browned and fragrant.

Add toasted hazelnuts to a food processor or mini chopper and pulse 5-6 times.

Add basil leaves, a pinch of kosher salt, freshly ground black pepper, and garlic cloves, then pulse 3-5 times until roughly combined.

With the machine running, slowly drizzle in olive oil until the pesto reaches your desired sauce consistency.

Add Parmesan cheese and pulse gently a few times to combine.

Taste and adjust seasoning with salt and pepper as needed.