Preheat the oven to 400°F (200°C).
Toss the baby potatoes with 1 tablespoon olive oil, minced garlic, salt, and pepper. Spread on a baking sheet and roast for 25-30 minutes until golden and crispy.
While the potatoes roast, heat the remaining olive oil in a large skillet over medium-high heat. Add 4 cloves minced garlic and sauté for about 1 minute until fragrant.
Season the chicken pieces with salt, pepper, and Italian seasoning. Add to the skillet and cook until browned and cooked through, about 5-7 minutes. Remove chicken and set aside.
In the same skillet, melt the butter and add sliced mushrooms. Cook about 6 minutes until mushrooms release juices and soften.
Lower heat and pour in heavy cream, stirring to combine. Simmer gently for 3-4 minutes until sauce thickens slightly.
Stir in grated Parmesan cheese until melted and sauce becomes creamy. Return chicken to skillet and toss to coat evenly with Alfredo mushroom sauce.
Remove roasted potatoes from oven and toss with fresh basil pesto until evenly coated.
Plate the creamy garlic mushroom chicken Alfredo alongside basil pesto potatoes. Garnish with chopped parsley if desired and serve immediately.