Line an 8x8-inch square pan with parchment paper, leaving an overhang on two sides to lift the bars out easily. Lightly grease the parchment with a little dairy-free butter or oil to ensure release.

Make peanut butter base

In a medium mixing bowl, combine 1 cup creamy natural peanut butter, 1/4 cup packed light brown sugar, 2 tablespoons pure maple syrup, 2 tablespoons melted dairy-free butter (or coconut oil), 1/2 teaspoon vanilla extract, and 1/4 teaspoon fine sea salt. Whisk or beat with a spoon until smooth and homogeneous. If using oats for structure, stir in 1/2 cup rolled oats now until evenly distributed. The mixture should be thick but spreadable—adjust with 1 teaspoon maple syrup or a little more peanut butter if needed.

Press base into pan

Transfer the peanut butter mixture to the prepared pan. Use a spatula or the back of a spoon to press it into an even layer about 3/4 inch thick, making sure edges are compacted and surface is level. Chill in the refrigerator for 10–15 minutes while you prepare the chocolate topping; chilling helps the layers set and prevents mixing.

Make chocolate topping

Place 1 1/2 cups dairy-free semi-sweet chocolate chips (or chopped dairy-free chocolate) in a heatproof bowl. Add 1 tablespoon coconut oil (or additional dairy-free butter). Melt gently: either microwave in 20–30 second bursts, stirring between each burst until smooth, or set the bowl over a pot of barely simmering water (double boiler), stirring until fully melted and glossy. Remove from heat and stir to remove any lumps.

Assemble and top

Remove the pan from the refrigerator. Pour the melted chocolate over the chilled peanut butter base and spread evenly with an offset spatula or back of a spoon to cover completely. If desired, sprinkle 1/4 teaspoon flaky sea salt evenly over the chocolate for a salted finish.

Set and chill

Return the pan to the refrigerator and chill for at least 1 hour, or until the chocolate is firm to the touch and the peanut butter layer has fully set. For quicker setting, place in the freezer for 20–30 minutes, but monitor so the texture doesn't become overly hard.

Slice and store

Use the parchment paper overhang to lift the slab from the pan onto a cutting board. Use a sharp knife warmed under hot water and wiped dry to make clean cuts; slice into 12 bars (3x4 grid) or into 9 larger bars (3x3). Store bars in an airtight container in the refrigerator for up to 2 weeks or freeze for up to 2 months. If frozen, thaw 10–15 minutes at room temperature before eating.