Preheat oven to 400. Cut the spaghetti squash in half and scoop out the seeds. Place the halves cut-side down on a foil lined baked sheet. Place them into the oven and set the timer for 10 minutes. (Total cook time is 35 minutes, but we add in the chicken and broccoli at different times throughout since they all take different amounts of time to cook!)
Add the chicken strips to a bowl and toss with 1 tbsp olive oil, the 1 tsp garlic powder, 1/2 tsp sea salt, and 1/4 tsp black pepper. Lay them out evenly on a separate parchment lined baking sheet. When the timer goes off, add the sheet pan with the chicken to the oven on the rack underneath the spaghetti squash. Set the timer for 25 minutes.
Toss the broccoli florets with the remaining 1 tbsp olive oil, 1/2 tsp sea salt, and 1/4 tsp pepper. When there is 15 minutes of cooking time remaining, add the broccoli to the sheet pan with the chicken. Use a spatula to flip the chicken and toss it all together. Return the pan to the oven for the remaining 15 minutes.
Make the alfredo sauce: combine all of the ingredients in a high-powered blender and blend on high for 1 minute. You can either leave it in the blender, or add the sauce to a small sauce pan and heat over low heat until the veggies and chicken are done cooking. If the sauce becomes too thick, you can add some chicken broth. Make sure to whisk it occasionally, as it will thicken on the stove.
Scoop the spaghetti squash strands out and serve it with the chicken, broccoli, and sauce on top. Enjoy!