Using a hand mixer or stand mixer, mix all ingredients together.
Liberally spray a 3-inch cake pan with cooking spray, ensuring to spray all sides and the bottom edges. Pour batter into cake pan. Cover with aluminum foil so the cake pan is covered entirely.
Pour 1 cup of water to the metal pot of your Instant Pot (or pressure cooker). Place metal trivet inside and position cake pan on top. Cover with lid and set valve to sealing.
Press Pressure Cook (HIGH) and set timer for 30 minutes. When cooking completes, allow pressure to naturally release for 10 minutes, then use a quick release to remove remaining pressure.
Allow cake to cool on the counter for 30 minutes, then place in the fridge to cool another 2+ hours.
When ready to position onto a plate, use a small knife to gently loosen the sides from the cake pan. Invert cake onto desired pan and gently shake the cake pan to get it to fall out.
Top with desired fresh fruit or your child's favorite foods, like a fun Cheerio boarder!
Store in the fridge until ready to use.
Recipe yields one smash cake, however nutrition analysis completed for 1/6th of cake (or the portion that most kids will actually eat). To make the cake in the oven, do not cover cake. Preheat oven to 350 degrees F and pour batter into greased cake pan. Bake for 45 minutes. Remove from oven, let cool, and then place covered in the fridge for minimum two hours. Remove from pan as directed above.