Begin by heating the oven to 180° C (350°F). Spread out your tomatoes on a parchment lined pan and toss with olive oil, salt, and garlic. Roast for 25-30 minutes.
In the meantime, get a large pot of water ready for the pasta. Put in on the stove as it will take a while to come to the boil.
Next, add all of the crumble mixture to a food processor or high-speed blender and blitz until it resembles that powdered parma. Add crumble to a bowl and set aside.
In the same blender or food processor, add all the pesto ingredients (of you're using a blender you'll end up with a more pureed mix, which is still fine) and puree until combined. I like mine with some super small bits of seeds left.
Once the water is boiling, cook the pasta (and hopefully time it so that it's done when the tomatoes will be ready). I used an organic wheat pasta, but gluten-free, or bean-based pasta would be great too.
By this point, everything should be near ready. Drain your cooked pasta and rinse with a little water so it doesn't stick together. Add the pasta to a bowl and stir in some pesto until you have a nice coating (I used about ¾ of the mixture). How much you use will all depend on the amount of pasta used and it's shaped, but you want it a little saucy. Stir in the roasted tomatoes followed by the handful of arugula, olives (if using), and extra basil leaves.
Toss together and sprinkle with the crumble mixture. More crumble can be added once it's served.