Microwave squash on high until tender, about 10 minutes. Shred the flesh of the squash and discard the skin.
Heat olive oil in a pan over medium heat. Once the oil begins to shimmer, add the garlic, red pepper flakes, and shrimp, and cook until shrimp are pink and start to curl, about 2 minutes.
Add the lemon zest, salt, pepper, and lemon juice, and cook for 1 minute.
Remove from heat, add parsley and shredded squash, and stir to combine.