Microwave the cream cheese 10 seconds until soft but not melted. Whisk with the sugar until completely smooth and lump-free.
Add the heavy cream, whole milk, peppermint extract, vanilla, salt, and food coloring. Whisk until fully combined and evenly colored.
Pour into a Ninja Creami pint, staying below the max fill line. Seal with the lid.
Freeze flat and level for 24 hours.
Remove the lid, lock the pint into the outer bowl, and run the ICE CREAM function.
If crumbly, run RE-SPIN. If still crumbly, add 1 tbsp milk and re-spin again until smooth and creamy.
Make a 1½-inch hole down the center of the pint to the bottom. Add the mini chocolate chips and brownie pieces. Run MIX-IN.
Spoon the warmed hot fudge over the top and fold in by hand, 2–3 strokes only, to keep the ribbon intact. Serve immediately.