In a large bowl or measuring cup, whisk together eggs and milk.

Add chopped bell pepper, green onion, salt, and pepper and stir to combine.

Spray down a round, heat-proof baking dish with cooking spray. (I used an 8-inch oven-safe corning ware dish that fits inside my instant pot.)

Pour egg mixture into dish and sprinkle cheese on top.

Pour 1½ cups of water into instant pot and place metal trivet inside. Place casserole dish on top of trivet.

Lock lid onto instant pot and cook on manual setting* at high pressure for 25 minutes.

Quick release the steam before removing the lid, and carefully remove casserole from instant pot.

Enjoy warm or cold! Package in an airtight container and refrigerate to store for up to a week.

Or, store in the freezer for up to 3 months. (Just know that frozen casserole is best enjoyed after thawing and reheating. It’s not ideal to enjoy cold after being frozen and thawed.)