Combine egg yolks, ¼ cup of milk and corn starch in a bowl. Whisk to mix.
In a medium to large bowl, combine egg yolk, wine, sugar and salt. Beat until it gets foamy.
In the meantime, core, peel and slice the apples into rounds (about 1/4 inch thick). Squeeze some lemon juice on the sliced apples to avoid discoloration.