Preheat oven to 400°F (200°C).

Line a sheet tray with silicone mat or aluminum foil.

Cut spaghetti squash in half lengthwise.

Scrape seeds out of each squash half.

Drizzle squash flesh generously with olive oil.

Season with salt, pepper, garlic powder, and dried parsley.

Roast squash for 45 minutes, or until tender and shreddable.

While squash roasts, heat olive oil in a large skillet over medium-high heat.

Add mushrooms and sun-dried tomatoes to the skillet.

Cook mushrooms and tomatoes until fragrant (2-3 minutes).

Add diced chicken to the skillet.

Cook chicken until completely cooked through, stirring frequently.

Season chicken mixture with salt, pepper, garlic powder, and dried parsley.

Stir in pesto sauce and simmer for 5 minutes on low heat.

Remove skillet from heat and set aside.

When squash is done, reduce oven temperature to 350°F (175°C).

Use a fork to shred the squash flesh into spaghetti-like strands, leaving it in the shell.

Divide the chicken mixture evenly among the squash boats.

Stuff the squash halves well with the chicken mixture.

Top each stuffed squash with a tablespoon of grated parmesan cheese.

Bake in the oven for 6-8 minutes, or until cheese is melted and bubbly.

Serve immediately and enjoy!