Grease a 6 cup round bundt pan with nonstick baking spray and set aside. To ensure the cake will come out of the bundt pan, dust the pan with cocoa powder and tap out any excess.
Add the butter, cocoa powder, sugar egg, and vanilla extract into a large mixing bowl. Beat with a hand mixer until combined.
Add in the sour cream, baking soda, and salt. Beat until incorporated.
Alternate adding the flour and beer to the batter until all ingredients are combined. Always start and end with the flour and scrape down the bowl after each addition.
Pour batter into the prepared bundt pan and cover with foil.
Add 1 cup of water into the instant pot (or 1 ½ cup depending on your manual) and place the trivet in the center of the pot.
Carefully place the pan full of cake batter on top of the trivet.
Lock the lid in place and turn the pressure release valve to the sealed position.
Set pressure to high and the time to 35 minutes. When the cheesecake is finished cooking and the pressure cooker beeps, release pressure doing a quick release.
Once the steam and pressure are gone, carefully remove the lid, and place the bundt pan onto a wire rack and allow it to cool completely
Once the cake is cooled, turn the cake out onto a wire rack over a cookie sheet.
Glaze
Add the powdered sugar, beer, and milk to a large mixing bowl. Whisk until the glaze comes together and is smooth.
Pour the glaze over the bundt cake and allow it to set up before cutting and serving.
Store in an airtight container at room temperature.