How to Make It
In a medium saucepan, warm the milk and cream. In a large bowl, combine the cream cheese and white chocolate. In a medium bowl, whisk the egg yolks with the sugar and salt until thick and pale. Gradually whisk the hot milk and cream into the yolks. Pour the mixture into the saucepan and cook over moderately low heat, stirring constantly, until it coats the back of a wooden spoon, 6 minutes; do not let it boil. Strain through a fine sieve over the cheese and chocolate. Let stand for 1 minute, then stir until smooth. Refrigerate until chilled, 4 hours.
Pour the custard into an ice cream maker and churn. Transfer the ice cream to an airtight container and freeze until firm, about 4 hours.
Preheat the oven to 350°. Butter and flour a 12-inch round cake pan. In a large bowl, whisk the flour with the sugar, cocoa powder, baking soda and salt. In a medium bowl, whisk the oil with the buttermilk, eggs, food coloring, vinegar and vanilla. Whisk the liquid ingredients into the flour mixture. Pour the batter into the prepared pan and bake for 40 minutes. Transfer the cake to a rack and let it cool completely in the pan, 2 hours.
Line a baking sheet with parchment paper. In a heavy, medium saucepan, combine the sugar and water. Cook over moderate heat without stirring until a deep amber caramel forms, about 15 minutes. Remove the pan from the heat and stir in the pecans. Pour the praline onto the parchment-lined baking sheet and spread in an even layer. Let cool until hardened, then chop medium-fine and transfer to a bowl.
Line the baking sheet with another sheet of parchment paper. Scoop 12 balls of the cream-cheese ice cream and set them on the baking sheet. Freeze the balls.
Slice the cake into 12 wedges and dust with confectioners' sugar. Transfer to plates. Roll the ice cream balls in the pecan praline. Serve with the cake.