In a bowl, place the ingredients for the cake and beat until soft and fluffy. In another bowl, place the ingredients for the custard and beat until the dulce de leche dissolves. Then, pour the cake mixture into the buttered savarin and carefully cover with the custard mixture, dropping first with a spoon to avoid deforming the cake mixture. Cover and cook over medium heat until fully cooked. We can serve it with a drizzle of dulce de leche or chocolate.