Preheat your oven to 180C and line a 24cm/8inch baking tin with baking paper.
Blend your oats into a fine flour using a food processor, blender or miller.
Add oat flour, flour, baking soda and salt to the bowl of a stand mixer, set aside.
Melt coconut oil in a pan along with peanut butter and maple syrup (or honey if you’re using that instead).
Add melted mixture to the dry ingredients. Add in the vanilla and milk and mix using the paddle attachment until fully combined.
Remove 1 cup of your cookie mixture and set aside for the crumble.
Press the remaining peanut butter cookie mixture into your baking tin. I use a smooth glass to roll over the mixture to pack it in tightly and create a level surface.
Bake for 8 minutes.
Remove from oven and let cool for 5 minutes.
Spoon your cup of jam over the par-baked peanut butter cookie mixture. Crumble the dough you set aside earlier over the jam. You can crumble it into big pieces.
Bake for another 10 minutes.
Remove from the oven and let cool completely before cutting into 16 squares.
Store in an airtight container for up to 4 days.