Ghee is already soft at room temperature, but if needed, transfer the ghee to a small dish and microwave for 10-20 seconds until fully softened.
Spoon about 1 tablespoon of melted ghee into 6 half globe molds, using a pastry brush, your finger, or the back of a spoon to coat the entire area all the way up to the very edges of the half circle. Set the mold in the freezer for about 10 minutes to chill it and firm the half globes. Set a plate in the freezer as well to chill it.
Remove the hardened shells from the molds and set them on the chilled plate. Spoon a bit of collagen and cinnamon (if using) into half of the molds.
Melt the coconut oil in a shallow dish in the microwave, just until it's melted. One at a time, take the unfilled half shells and dip the wide side gently in the melted coconut oil. Place it facedown on top of a filled half shell, then rub your fingers around the entire sealed area to close up the edges. Your fingers will get a little buttery, so just keep a towel nearby to wipe your hands after each one. Set the sealed ball in a muffin cup liner or back on the plate, and put it back in the freezer for at least 5-10 minutes.
Mix the cocoa powder into the remaining melted coconut oil until smooth. Drizzle about 1/2-1 teaspoon of the mixture over each the ghee balls, then sprinkle it with the pink sea salt. Set back in the freezer until you're ready to serve.
Fill a large coffee mug with 1 cup of freshly brewed, hot coffee, not more than 2/3 of the way to the top of the mug. Add one of the bombs, then wait until it melts enough so that it bursts. You can use a spoon to stir it completely use a milk frother to blend and serve.
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Notes
To store: The bulletproof coffee bombs need to stay cold. Store them in an airtight container in the freezer and remove just before serving. To make vegan friendly bulletproof coffee: Do not use ghee, and instead, substitute coconut oil. Do not use collagen powder and substitute any vegan protein powder.