In a large bowl, whisk together the milk and egg; add the Panko breadcrumbs and stir to combine; set aside until all the milk has been absorbed.
Meanwhile, mince the onion, garlic, carrot, celery, and parsley together.
Into the same large bowl, add the ground beef, salt, and black pepper along with the minced onion, garlic, carrot, celery, and parsley and mix together completely.
Once combined, form the mixture into a loaf and place on a sheet of aluminum foil making sure the meatloaf fits into your pressure cooker.
Fold the sheet of aluminum foil up and around the meatloaf to form a packet.
To prevent potatoes from splitting during cooking, pierce with a fork so steam can escape.
Add the potatoes and carrots into the bottom of the pressure cooker and add the water. Place an inverted steamer basket, small roasting rack or the steaming rack that may have come with the instant pot (affiliate link) onto the vegetables.
Place the meatloaf in its aluminum foil packet on top of the rack; be sure to leave room around the edge to allow steam to rise to the top of the pot (to close the pressure valve).
Cover with the lid and twist the handle to lock the pressure cooker. Be sure to make sure the pressure release valve is set to sealing.
Select Manual and cook at High Pressure for 20 minutes. Allow 15 to 20 minutes for the pot to pressurize before the cook cycle begins.
Turn off the pressure cooker off and release the steam valve by quick release being careful of the steam. Once the pot has released the pressure, carefully open the lid.
Confirm the meatloaf’s internal temperature is at least 145 degrees F, the center is cooked and the juices run clear.
Serve immediately with or without the optional glaze.
Traditional vs. Instant Pot. The time difference for meatloaf cooked in the instant pot (11 psi) vs a traditional pressure cooker (15 psi) is nominal. Since the higher pressure cooks faster, if you adapt this for a conventional pressure cooker, shorten your cook time by 2-3 minutes (17-18 minutes cook time).
Water - use 1 cup or the minimum liquid requirement for your machine.
Ketchup Glaze. Nutrition is calculated based on the recipe as written including the potatoes and carrots. The addition or omission of ingredients will alter the nutritional information.
Double the Recipe. To double this you can make two smaller smaller loaves side by side on the rack or create one larger 2-pound meatloaf. If you choose the latter, increase the cook time to 30 minutes on high pressure. When the timer is up you can do a quick release of the steam button. After all the steam has released, carefully remove the lid and check to make sure your meatloaf is done. The internal temperature should be 145 degrees F and the juices should run clear.
Cooking times you see on recipes are usually after the instant pot has been pressurized. This is because the time to become pressurized and de-pressurized is not the same for all recipes. Pressurization time depend on the amount of liquid, volume of food in the pot, fat content, and altitude.
I have made a note on the recipe to add an additional 20 minutes for pressurization to occur.
At sea level with a 1.5-pound meatloaf and 3 pounds of vegetables, my instant pot took 15 minutes to pressurize.
The manual button is an all-purpose button. Use the manual button if a recipe says to pressure cook on high pressure for a specific number of minutes. Use the “+” and “-” buttons to increase or decrease the cooking time.
Many Instant Pot recipes mention the Manual button. The Manual button was replaced by the Pressure Cook button on newer models of the Instant Pot.
For the CrockPot Instant Pot, the manufacturer recommends using the "Beans/Chili" function when using a recipe that calls for “manual” adjustments. This function allows you to adjust the pressure to LOW or HIGH and set cook times from 5 minutes to 2 hours.
Nutrition is calculated based on the recipe as written. Additions, omissions, or substitutions will change the calculated values shown. The addition, omission, or substitution of ingredients will alter the nutritional information shown. Nutrition percentages are based on a 2000-calorie diet. The FDA recommends 80 micrograms of vitamin K.