Season chicken on all sides with garlic powder, salt, and pepper.
Using the saute mode, heat the electric pressure cooker until “hot.” Add the olive oil and chicken breast, cooking until browned on both sides, about 3 minutes each. The chicken will not be cooked through.
Remove the chicken and keep warm. Deglaze the bottom of the liner with chicken broth by pouring the broth into the liner and scraping the bottom with a flat- edged wooden spoon. Cancel the saute mode.
Return the chicken to the pressure cooker. Top with penne, pressing the pasta down into the liquid. Do not stir.
Place the lid on the electric pressure cooker and set the valve to sealing. Set the pressure cooker to “manual” or “pressure cook” for 6 minutes. Quick release the pressure when the cook cycle is complete.
Stir 2 cups of cheese, heavy cream, and broccoli into the pasta. Top with remaining cheese. Replace the lid, allowing the pressure cooker to remain in the “keep warm” setting until the broccoli is warmed through and the liquid is absorbed.