For example, chocolate mousse cake is made by mixing oil and milk in a clean bowl until emulsified.Sift in the flour mixture and cocoa powder and mix well.Add egg yolk and mix well;Add sugar to egg whites in three batches and beat to a sharp corner. Preheat the oven to 180 degrees.Take a third of the egg white and egg yolk paste and mix well;Pour the egg yolk batter into the remaining two-thirds of the egg white batter and stir well.Pour the mixed paste into the baking pan, smooth and shake it a few times, put it into the preheated oven at 180 degrees for 25 minutes, take it out and cool it.Pale cream and powdered sugar beat to six or seven distribution reserve;Place the gelatin sheet in cold water until soft. Heat the milk and chocolate in a small saucepan over medium heat (or over water). When it is hot, turn off the heat and mix the chocolate and milk.When the temperature of the milk chocolate paste is below 50 degrees, stir the softened gelatin sheet.Mix the chocolate batter with the whipped cream until smooth.Add Oreo and mix well;Place the mousse ring on a base (or flat plate). Place one piece of cake inside the mousse ring. Pour half of the mousse batter over the top of the cake to smooth it.Take another piece of cake and put it on top. Pour in the rest of the mousse batter.Heat the light cream and chocolate in a small saucepan over medium heat. Turn off the heat before the milk comes to a boil and mix well.Let the batter cool and pour over the mousse cake. If there are any bubbles on the top, use a toothpick to pop them.Refrigerate for at least 2 hours. Remove and rub mousse with a hot towel around the ring. Remove and cut mousse into small pieces