Cook spaghetti in a large saucepan of boiling water, following packet directions
Drain spaghetti reserving ¼ cup cooking water and set pasta aside.
Meanwhile, to make the pesto, place spinach into a medium heatproof bowl. Pour over boiling water, toss until leaves wilt. Drain well and squeeze spinach dry.
Scoop avocado flesh into a food processor and add spinach, lemon juice, oil, garlic, basil and toasted pine nuts. Process until smooth.
Stir through parmesan.
Heat olive oil in the saucepan over medium heat; add tomatoes and cook, tossing, until hot.
Add spaghetti, reserved pasta water and pesto to pan.
Gently toss over heat until just combined.
Place in a large serving bowl and sprinkle with extra basil leaves, grated parmesan and season to taste.
Serving Size 4