Line an 8x8-inch or 9x9-inch baking pan with parchment paper.
Combine the melted butter, crumbs, powdered sugar, and vanilla in a mixing bowl and stir well. (You can also do this in a food processor – my preferred way since the dough gets a bit stiff.) Add the SunButter and stir until fully combined. Press the mixture firmly and evenly into the prepared pan.
Melt the chocolate chips and 2 tablespoons butter over barely simmering water (making sure the bottom of the pan does not touch the water) or in the microwave. Stir until smooth and glossy. Spread the chocolate evenly over the SunButter mixture and smooth with an offset spatula. Sprinkle the salt over the top. Refrigerate until fully firm, at least 2 hours. Remove from the refrigerator and allow to sit at room temperature for 15-20 minutes. Using the parchment paper, transfer from the pan to a cutting board and cut into squares or rectangles.
Store cut bites in the refrigerator until serving time.