Instant Pot Cottage Pie

Turn on your pressure cooker and switch to the Sauté mode. Heat a generous amount of oil in the pot, then sauté ground beef, chopped onion, minced garlic, salt, and pepper over high heat until the meat is nicely browned and crumbly, while the onion softens and becomes translucent, approximately 5 minutes. Introduce tomato paste, Worcestershire sauce, and thyme into the mixture, stirring to combine. Add broth, then stir in frozen peas and carrots until they're fully incorporated into the dish. Switch off the Sauté function.

Position the collapsible metal trivet in the pot, positioning it just above the meat-vegetable mixture. Place diced potatoes on the trivet. Close and secure the lid, then select high pressure according to your manufacturer's guidelines. Set a timer for 15 minutes if the potatoes are on the smaller side, or 20 minutes if they're medium or large. Allow for 10 to 15 minutes for the pressure to build.

Release the pressure using the natural-release method according to your manufacturer's instructions, letting it sit for 10 minutes. Release any remaining pressure carefully using the quick-release method according to your manufacturer's instructions, taking about 5 minutes. Open the lid and transfer the potatoes to a bowl. Switch off your pressure cooker and carefully remove the hot trivet.

Add half-and-half, butter, and garlic salt to the potatoes in the bowl; mash until well combined.

Set an oven rack about 6 inches from the heat source and preheat your oven's broiler.

Transfer the meat-vegetable mixture from the pressure cooker into an 8-inch square baking dish. Spoon mashed potatoes on top and spread out evenly.

Place the dish under the preheated oven's broiler until the top starts to turn golden and brown, approximately 3 minutes.