Preheat the oven to 400°F (200°C). Line a baking sheet with parchment paper or foil.
Slice the spaghetti squash lengthwise and scoop out the seeds with a spoon.
Place the squash cut-side up on the prepared baking sheet. Lightly brush or spritz the flesh with olive oil and season with salt and black pepper.
Roast the squash for 30–35 minutes, or until the strands easily separate from the sides with a fork.
While the squash is finishing, melt the butter in a skillet over medium-low heat. Add the minced garlic and cook about 30 seconds until fragrant.
Stir in the lemon juice and lemon zest, then season with a pinch of salt and the 1/4 teaspoon cracked pepper. Bring briefly to a simmer, then remove from heat.
Use a fork to scrape the roasted squash flesh into strands and transfer to a bowl or plate.
Toss the squash strands with the warm lemon butter until evenly coated.
Sprinkle the crumbled feta, toasted sliced almonds, and chopped fresh herbs over the squash. Gently toss to combine and serve immediately.