Preheat oven to 350℉ and line an 8x8 pan with parchment paper.
In a bowl using a hand mixer or a stand mixer, whip the butter and sugar until fluffy. Mix in the egg, extracts, and agave until smooth.
Mix in the baking powder, almond flour, coconut flour, and tapioca flour until you have a dough. Fold in the freeze dried strawberries.
Press the cookie dough into the prepared pan and bake for about 15-20 minutes, depending on how soft you want them.
In the meantime, make the buttercream. Whip the butter until fluffy. Slowly incorporate the powdered sugar until you have a texture you like. Add in the vanilla extract and optional milk to thin. Once you have a frosting consistently you like, fold in the strawberries.
Spread the frosting evenly over the baked cookie bars, slice, and enjoy!