For custard, in a heavy medium saucepan, combine sugar and cornstarch. Stir in milk. Cook and stir over medium heat until mixture is thickened and bubbly. Cook and stir for 2 minutes more. Remove from heat. Gradually whisk about half of the hot mixture into the eggs. Return all of the egg mixture to the saucepan. Reduce heat to low. Cook and stir for 2 minutes more. Immediately pour custard into a medium bowl; whisk in sour cream and Marsala. Cover the surface with plastic wrap. Chill for 2 to 24 hours.
To serve, divide custard among 8 dessert dishes. Top with fruit and, if desired, cinnamon and mint.
Tip: If using sugar substitutes, we recommend Splenda® Granular or Sweet'N Low® bulk or packets. Follow package directions to use amount equal to ¼ cup.