Heat the oven to 200°C (390°F) and place a block of feta in the center of a large oven-safe pan.
Drizzle 1 tablespoon of olive oil over the feta and roast in the oven for about 8 minutes until it softens.
Add the halved cherry tomatoes and chopped asparagus around the feta, drizzle with remaining olive oil, then return the pan to the oven and roast for another 12-15 minutes until vegetables are tender.
While the vegetables roast, bring a large pot of salted water to a boil and cook the orzo pasta according to package instructions until al dente.
Drain the orzo and return it to the pot, then stir in the mascarpone cheese, chopped basil, fresh chives, baby spinach, and season with salt and black pepper to taste.
Once the feta and vegetables are roasted, mix them gently into the orzo and give everything a final stir to combine evenly.
Serve warm, garnished with extra herbs if desired.