Start by preheating your oven to 350°F (175°C). Spray your cake pan or ramekin with cooking spray or lightly grease with coconut oil. This ensures the cake won’t stick and comes out cleanly.
I ground the oats into a fine powder using my blender. This step is key for a smooth cake texture. Skip this, and the cake might turn out lumpy.
Combine the ground oats and baking powder in a bowl using a whisk. I like to whisk them first so the leavening is evenly distributed, giving the cake a gentle rise.
Add peanut butter, applesauce, and the egg to the dry mix. Stir with a spatula or use an electric mixer until smooth. The batter should be thick but pourable.
Pour the batter into your prepared pan and bake for 25 minutes. I always check with a toothpick; if it comes out clean, the cake is ready. Let it cool before frosting.
Mash the blueberries and stir them into the Greek yogurt until creamy. I like to make it just before serving to keep it fresh and colorful.
If making a two-layer cake, spread frosting between layers and on top. Decorate with extra blueberries or dog-friendly treats. My dog loved it, and the presentation was super cute!