Using the saute function of your pressure cooker, heat the oil. Add the onion, jalapeno, and garlic; cook 3-4 minutes, or until softened.
Stir in the chili powder, then pour in the macaroni, beans, tomatoes, and vegetable stock.
Lock the lid, making sure it's set to "sealing." Cook on high pressure for 4 minutes.
Manually release the pressure.
Carefully remove the lid and stir in corn and the cheeses.
If desired, top the chili mac with cilantro, sliced jalapenos (fresh or pickled), or diced avocado.