Preheat the oven to 350°. Bring a large pot of water to a boil. Add the spaghetti squash and cook until it is al dente, about 12 minutes; drain. Place the spaghetti squash halves cut side down on a rack and let cool for 15 minutes.
Meanwhile, spread the sliced almonds on a pie plate and toast them in the oven for about 7 minutes, until lightly golden. In a mini food processor, combine the chopped olives with the sliced scallions, lemon zest, lemon juice and canola oil and pulse until finely chopped.
Working over a medium bowl and using a fork, scrape the spaghetti squash into the bowl, separating the strands. Add the dressing along with the crumbled feta and toasted almonds and season with salt and white pepper. Toss the spaghetti squash salad and serve warm.