Preheat oven to 350 degrees. Line a 9 x 9 inch cake pan with parchment paper.
In a large bowl, beat together the melted coconut oil, maple syrup, and vanilla. Add in the flour and beat until just combined and a soft, cohesive dough forms.
Press the dough evenly into the bottom of the cake pan. Bake for 12-15 minutes until slightly golden. Set aside.
In a small saucepan, combine the peanut butter, maple syrup, and coconut oil. Bring to a boil and heat, whisking constantly, for 2 minutes. Pour the mixture over the shortbread layer. Cover and freeze 30 minutes.
Add the chocolate chips and coconut oil to a microwave-save dish or bowl. Heat in 30 second intervals, stirring in between each, until melted and smooth. Let cool 5 minutes, then pour over the peanut butter layer. If desired, make cute little swirls with a skewer or knife, or pipe thin drizzles of chocolate over the top. Sprinkle with flaky salt. Set in the fridge for 15 minutes to harden.
Slice into 16 bars and serve with coffee or hot chocolate.
Notes
*To store: Bars keep well covered in the fridge for up to a week. *Dark chocolate: Be sure your choice brand of dark chocolate is vegan certified if that is a concern to you.