Mix together eggs, vegetable oil, sugar and vanilla.

Mix in the baking soda, baking powder, salt, flour, and cinnamon. Fold in the zucchini and walnuts.

Spray a 7-inch baking pan with nonstick cooking spray.

Spread the batter into the pan.

Add 1 ½ cups of water to the inner pot of the Instant Pot.

Cover the pan with foil and using either the sling method or a trivet with handles, lower the pan into the instant pot.

Close the lid of the Instant Pot and turn to sealing position.

Set for a manual high-pressure time of 60 minutes. When the time has finished, allow for a natural release.

Cool on the counter for an hour and then run a fork around the edge of the cake if needed to loosen before tipping the cake out of the pan.