Line your mold: Use a silicone mini-muffin mold or a silicone ice cube tray.
If using a metal mini-muffin tin, add paper liners.
Warm the base: In a small saucepan over low heat, melt the coconut oil and butter together. Stir gently until just melted, not sizzling.
Add peanut butter: Whisk in the peanut butter until smooth and fully combined with the fats.
Sweeten and flavor: Remove from heat. Whisk in the powdered sweetener, vanilla, and salt.
Taste and adjust sweetness.
Make it chocolatey: Sift in the cocoa powder to prevent lumps. Whisk until glossy and uniform. If adding chocolate chips, fold them in now so they soften but don’t fully melt.
Fill the molds: Spoon the mixture evenly into 12–16 mini cavities, about 1 to 1.5 tablespoons each.
Tap the tray lightly to level.
Add a finishing touch: Sprinkle with a pinch of flaky sea salt or a few crushed peanuts if you like contrast.
Chill to set: Refrigerate for 1–2 hours or freeze for 25–30 minutes until firm.
Pop and store: Gently release each fat bomb from the mold and transfer to a container for storage.