Preheat the oven to 350 degrees Fahrenheit and line a 8-inch square pan or round cake pan with parchment paper. I strongly recommend using parchment paper as opposed to cooking spray for this recipe to make it easier to get the cake out of the pan.

Transfer the oats to a high-speed blender and blend for 30 seconds to 1 minute, or until a flour forms. Add the rest of the dry ingredients (baking powder sea salt, and pumpkin pie spice) to the blender and blend for a few seconds to combine.

Transfer the dry ingredients to the mixing bowl with the wet ingredients and mix well.

Stir the chopped apples (or shredded apples) into the cake batter. Note: if you'd like to toss the apples in 1 tablespoon of flour to prevent them from sinking to the bottom of the pan, you can!

Pour the cake batter into the prepared pan and spread it into an even layer using a rubber spatula. If you'd like, you can add more apple pieces to the top of the batter.

Bake for 23 to 28 minutes in the preheated oven, or until the top of the cake is golden brown. Cakes are fully baked when they reach an internal temperature of 190 degrees F. You can insert an instant read thermometer into the center of the cake to verify it is done.

Remove the cake from the oven and allow it to cool completely to room temperature.

Pull on the edges of the parchment paper to release the cake from the pan and transfer it to a cutting board. Slice the cake into individual slices and enjoy!

If you're eating this cake for breakfast, I recommend pairing it with a quality protein source like Greek yogurt, scrambled eggs, leftover animal protein, etc.