Instant Pot Frittata

Generously grease an 8" metal cake pan with cooking spray. Set an 8-quart Instant Pot to Sauté on high temperature. Add chopped bacon, and cook, stirring occasionally, until browned, about 8 minutes. Using a slotted spoon, remove bacon to a paper-towel lined plate and set aside.  Add onions to pot and cook, stirring occasionally and scraping bottom of pan to release golden bits, until softened, about 3 minutes. Add spinach and cook until wilted, 3 minutes, then transfer to plate with bacon. Clean out pot insert.  In a bowl, whisk together eggs, milk, and salt until well combined. Fold in cooked bacon, vegetable mixture, and roasted pepper. Pour mixture into prepared cake pan and top with cheddar. Add 1 ¼ cup water to pot. Cover cake pan with foil, place on trivet, and lower into pot. Lock lid and set to Pressure Cook on high for 30 minutes. Follow manufacturer’s guide for quick release, making sure to wait until cycle is complete before unlocking and removing lid. Carefully, using handles on the trivet, remove cake pan from pot.  If desired, preheat oven to broil and transfer cake pan to oven. Broil until cheese is golden, 2 minutes. Let cool 10 minutes before slicing.