Pre heat the oven to 390F / 220c.
Place the tomatoes on a parchment lined tin, drizzle with a little oil and roast for 15 to 20 minutes until soft. Place to one side.
Add the oil, basil, sugar and lemon juice to a blender. Blend on high speed until well mixed.
Cook the orzo pasta according to package instructions; cook in salted boiling water for 5 to 6 minutes.
While the pasta is cooking, roughly chop the baby spinach.
Drain the spinach and transfer to a large bowl. Stir the spinach in straight away so that the pasta is still warm and the spinach wilts a little.
Pour over the basil oil and stir until combined.
Let sit for 30 minutes before serving with the roasted tomatoes.