In a medium bowl, use a rubber spatula to mix together the almond flour, melted butter, peanut butter and honey substitute.
Use the spatula to transfer the mixture to a wax-paper-lined, 8-inch square pan, and to spread the mixture evenly.
Place the chocolate chips and the butter in a microwave-safe bowl. Microwave in 30-second increments, stirring after each microwave session, until almost fully melted. Stir the mixture with a rubber spatula until fully melted.
Pour the melted chocolate on top of the peanut butter mixture, using the spatula to scrape it off the bowl and to spread in evenly. Work gently, so that the chocolate layer stays on top of the peanut butter layer.
Cover the pan with plastic wrap. Refrigerate until set and firm, about 4 hours.
Carefully lift the wax paper and place it on top of a cutting board. Using a sharp chef’s knife, cut into 16 squares.
Keep leftover peanut butter chocolate bars refrigerated in an airtight container, separated by layers of wax paper. Remove from fridge five minutes (but no longer, or they become too soft) before serving.