Prep your pan. Line an 8x8-inch pan with parchment, leaving overhang on two sides for easy lifting. Lightly grease the parchment to prevent sticking.
Gently melt the base. In a small saucepan over low heat, add the chocolate and coconut oil (or butter).
Stir constantly until just melted and smooth. Remove from heat right away to avoid scorching.
Stir in nut butter. Whisk in the almond or peanut butter while the mixture is warm. It should become thick, glossy, and uniform.
Sweeten and season. Add the powdered keto sweetener, vanilla, and a pinch of sea salt.
Whisk until the sweetener dissolves. Taste and adjust sweetness. If it’s too thick, warm it gently for 10–15 seconds.
Add your mix-ins. Fold in chopped nuts, shredded coconut, and cacao nibs or sugar-free chips if using.
Keep a handful of mix-ins aside to sprinkle on top for looks.
Pan and level. Scrape the mixture into the lined pan and spread it into an even layer with a spatula. Tap the pan on the counter to release any air bubbles. Sprinkle remaining mix-ins and a pinch of flaky salt on top.
Chill to set. Refrigerate for 1–2 hours, or until firm enough to slice.
For a faster set, place in the freezer for 30–45 minutes, but don’t forget it there or it may become too hard to cut neatly.
Slice and serve. Use the parchment overhang to lift the slab out. Warm a sharp knife under hot water, wipe dry, and slice into 16–20 bars. Serve slightly chilled for the best texture.