Bring a large pot of salted water to a rolling boil and cook orzo until al dente, approximately 9 minutes.

Drain the orzo and rinse immediately under cold running water to stop the cooking process and remove excess starch.

Place pine nuts in a dry skillet over medium-low heat and toast for 3-5 minutes until golden brown, stirring frequently.

In a large mixing bowl, whisk together the basil pesto and lemon juice to thin the consistency.

Add the cooled orzo to the bowl and toss thoroughly until every grain is coated in pesto.

Fold in the cherry tomatoes, mozzarella pearls, toasted pine nuts, and spinach.

Season with salt and black pepper, then refrigerate for at least 30 minutes before serving to allow flavors to integrate.