Preheat oven to 350°F. Line an 8x8 inch pan with parchment paper or lightly grease.
In a large bowl, whisk together almond flour, oat flour, baking soda, and salt.
In a separate bowl, whisk together melted coconut oil, nut butter, maple syrup or honey, whole egg, egg yolk, and vanilla extract until smooth.
Add wet ingredients to dry ingredients and stir until just combined.
Press dough evenly into the prepared pan.
Bake for 13 to 15 minutes, until edges are set and lightly golden while the center remains soft.
Allow bars to cool completely in the pan.
To make the frosting, mix cream cheese, Greek yogurt, honey or maple syrup, and vanilla until smooth.
Spread frosting evenly over cooled bars.
Slice into squares and store in an airtight container in the refrigerator.