While the spaghetti is cooking according to the package instructions.
In the meantime, cut the spring onions into rolls, the 3 piri piri (chili peppers) into small pieces and the garlic cloves into slices.
Let the olive oil get hot in the pan and fry the vegetables in it for about 5 minutes. Then add the crabs and just let them get hot. Pour the whole thing over the drained spaghetti.