Place milk, malted milk powder, sugars, yolks and salt into the Thermomix bowl and cook 8 min/80°C/speed 4.
Add vanilla and using a microplane, finely grate the truffle into the hot custard. Allow to infuse in the Thermomix bowl and at least 10 minutes.
Add the cream and blend 20 sec/speed 8.
Pour into a jug or container that will not retain the heat, and cover with a cartouche. Bring to room temperature before transferring to the fridge for several hours until completely chilled. (Overnight is fine, aging the custard is a really good thing for flavour.)
Churn in an ice cream churner, following the manufacturers instructions. Alternatively, freeze in an ice cube tray and then transfer half the frozen blocks into the Thermomix bowl and chop 6 sec/speed 8 Add remaining blocks and with the aid of the Thermomix spatula, blend and whip until creamy.
If adding in malteasers, wrap them in a silpat mat, (you know the one I mean!) and bash them a couple of times with a rolling pin. This cannot be done in the Thermomix bowl unless you want dust.
Combine into the churned or blended ice cream right at the end. Freeze for a couple of hours before serving.