Warm the base: In a small saucepan over low heat, gently melt the coconut oil and butter.
Stir until smooth. Avoid boiling.
Add hazelnut butter: Whisk in the hazelnut butter until fully combined and glossy.
Flavor and sweeten: Remove from heat. Whisk in cocoa powder, sweetener, vanilla, and salt.
If using cream, whisk it in now for a silkier texture. Taste and adjust sweetness.
Optional crunch: Fold in chopped toasted hazelnuts.
Portion: Spoon the mixture into silicone mini muffin molds or candy molds. No molds?
Line a small loaf pan with parchment and pour it in.
Chill: Refrigerate for 45–60 minutes, or freeze for 20–30 minutes, until firm.
Optional drizzle: Melt sugar-free chocolate chips with coconut oil. Drizzle over the set fat bombs and chill again for 5–10 minutes.
Serve: Pop out of molds or slice into squares if using a loaf pan. Keep chilled until ready to eat.