PREPARE THE PEANUT BUTTER LAYER:

1. Line an 8×8″ or 9×9″ square pan* with parchment paper. I prefer to leave excess parchment hanging over the edge to make it easier to smooth out the peanut butter layer later.
2. In the bowl of a food processor (or in a bowl with a spoon!), combine peanut butter, oat or almond flour, maple syrup, vanilla, and salt.
3. Puree or mix together until smooth and cohesive (no lumps should remain)
4. Transfer the peanut butter mixture to prepared baking dish and smooth out the layer with a spatula, your fingertips, or by folding the excess parchment hanging over the sides of the pan over the peanut butter layer and pressing down the and smoothing that way (see video for example)

PREPARE THE CHOCOLATE LAYER:

1. In a small saucepan, combine chocolate chips and peanut butter.
2. Stir with a spatula over low heat until the chocolate and peanut butter have melted together and the mixture is smooth. (Alternatively, you can microwave the chocolate and peanut butter together in a microwave safe bowl 30 seconds at a time, stirring in between until the chocolate is smooth and evenly melted.)

ASSEMBLE THE BARS:

1. Pour melted chocolate mixture over the peanut butter layer in the pan and smooth gently with a spatula until the peanut butter layer is evenly coated.(For a super-smooth top, gently shake the pan side to side to even out the chocolate.)
2. Refrigerate the bars about 1 hour to set and firm up. (or put them in the freezer to speed things up!)
3. Remove from the refrigerator and let sit about 10 minutes before slicing into even squares. If desired, sprinkle with coarse sea salt right before serving.
4. Store leftover chocolate peanut butter bars covered or in an airtight container in the refrigerator up to 1 week or in the freezer up to 2 months.