Preheat your oven to 350 degrees and rub a 8x8 inch baking pan with oil.
In a medium microwave safe bowl melt the peanut butter and honey until smooth and melted, about 1 minute. Sprinkle the coconut sugar on top and let stand for 5 minutes.
While the coconut sugar stands, mix the oats, oat flour, powdered peanut butter, protein powder, baking soda, baking powder and salt in a medium bowl until well mixed.
Whisk together the coconut sugar and peanut butter mixture. Add in the kefir, egg yolk and vanilla and whisk until smooth. The mixture will thicken a lot.
Add the dry ingredients into the wet and whisk until well combined.
Spread 1/2 of the dough into the bottom of the prepared pan. Spread the preserves evenly over top. Drop the remaining dough in little clumps over top of the preserves and then use a spatula to smooth out to cover the preserves.
Bake until a toothpick inserted comes out clean (a little bit of preserves on the toothpick is fine!) which is about 30-35 minutes. Place a hot pad into your refrigerator and place the pan immediately on it in the fridge for 15 minutes. *
After 15 minutes, return to the counter and let the bars cool in the pan completely.
Slice and DEVOUR!
*The refrigeration is the key to making them soft and chewy as it rapidly stops the cooking time. Don't leave the bars in there longer than 15 minutes though or you will heat up your fridge!