Combine the milk and cooking cream in a pot and put them to heat on the stove. Then mix with the sugar until dissolved.
Dissolve the starch in a little cold water and under continuous stirring, add it to the milk. Stir until the cream thickens nicely. Remove from the heat and mix in the crushed white chocolate. Leave it to sit for a minute until the chocolate softens and then stir until everything becomes homogenized.
In appropriate dessert cups, put 1-2 biscotti each. Spread the cream on top and sprinkle it with plenty of mocha coffee.
Put the dairy mocha cream with biscotti for 3 hours in the refrigerator before serving.