Prep the sweet potato: Peel and cube the sweet potato. Steam or microwave until very tender. Mash well and cool to room temp. You need 1 cup mashed.

Prepare the pan: Grease a 7-inch round cake pan (or 6-cup Bundt, if it fits your cooker). Line the bottom with parchment and grease again. Cover the top tightly with foil for steaming.

Set up the pressure cooker: Add 1 1/2 cups water to the pot and place the trivet inside. You’ll lower the pan onto this so it doesn’t sit in the water.

Mix dry ingredients: In a medium bowl, whisk flour, baking powder, baking soda, salt, cinnamon, and nutmeg.

Whisk wet ingredients: In a large bowl, whisk eggs, maple syrup, brown sugar, oil, milk, vanilla, lemon zest (if using), and the cooled mashed sweet potato until smooth.

Combine: Add dry ingredients to wet. Stir gently just until combined. The batter will be thick and silky—avoid overmixing.

Fill the pan: Scrape batter into the prepared pan. Smooth the top. Tap lightly to release air bubbles. Cover tightly with foil.

Pressure cook: Lower the pan onto the trivet. Seal the lid. Cook on High Pressure for 45 minutes.

Release and check: Let pressure naturally release for 10 minutes, then quick release the rest. Carefully lift out the pan. Remove foil. A tester should come out clean or with a few moist crumbs. If underdone, re-cover and cook 5–7 minutes more at High Pressure with a quick release.

Cool: Let the cake cool in the pan for 15 minutes. Run a knife around the edge, invert onto a rack, peel off parchment, and flip upright. Cool at least 30 minutes before slicing.

Optional finish: Brush the warm cake with 1–2 tablespoons maple syrup for shine and extra flavor. A dusting of powdered sugar or a spoon of yogurt or whipped cream also works.