Prepare the pan: Grease a 7-inch cake pan and line the bottom with parchment. Lightly grease the parchment too. Set aside.

Bloom the oats (optional but helpful): In a bowl, stir the rolled oats with the milk and let stand 10 minutes. This softens the oats so the cake bakes evenly.

Mix dry ingredients: In a large bowl, whisk flour, brown sugar, granulated sugar, baking powder, baking soda, salt, and cinnamon until no lumps remain.

Add wet ingredients: To the oat-milk mixture, whisk in yogurt, oil, eggs, and vanilla until smooth.

Combine batter: Pour wet ingredients into dry and stir gently until just combined. Do not overmix.

Fold in chocolate chips: Toss chips with a teaspoon of flour first if you want to prevent sinking, then fold into the batter.

Fill the pan: Scrape the batter into the prepared pan and smooth the top. Sprinkle a few extra chips on top for looks.

Set up the cooker: Add 1 to 1 1/2 cups water to the pressure cooker. Place a trivet inside. Make a foil sling if your trivet doesn’t have handles.

Load the cake: Place the pan on the trivet. Cover the top of the pan loosely with foil to prevent condensation from dripping onto the cake.

Pressure cook: Seal the cooker. Cook on High Pressure for 35 minutes. (For a deeper pan or very dense batter, go up to 38–40 minutes.)

Release pressure: Let it naturally release for 10 minutes, then quick-release any remaining pressure.

Check doneness: Uncover carefully. A toothpick inserted in the center should come out with a few moist crumbs but no wet batter. If undercooked, reseal and cook 3–5 more minutes.

Cool: Lift out using the sling. Cool the cake in the pan for 10–15 minutes, then run a knife around the edge and turn out onto a rack. Peel parchment and flip upright. Cool until just warm.

Serve: Slice and enjoy warm or at room temperature. A drizzle of warm chocolate or a dollop of yogurt or ice cream is a nice touch.