With a bit of luck, this is only the hydraulic valve tappets which are empty of oil, assuming that the lost of oil pressure (during the had braking) forced the oil in the top of the engine to drop down to the pan...

There is a procedure recommended by BMW as this is something which can occur on vehicles doing very frequent short rides, (start the engine and while keeping the transmission in neutral, accelerating the engine to 2500 to 3000 rpm during 3 minutes, then letting it idling again for 5 minutes. In some cases they recommend to do that several times with a maximum of 5.), however before doing that you have to check first where the noise is located exactly.

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BMW X5 2001 3.0I
ALFA-ROMEO Mito Turbo-Jet
Many mythical italian brand Laverda motorbikes...