In a medium-size, nonreactive saucepan over medium heat, combine the milk, cream, sugar, and vanilla bean and pulp. Whisk to dissolve as the mixture heats. Heat the mixture to the scalding point (when bubbles form around the edges of the pan); do not let it boil. Remove from the heat. Beat the egg yolks in a large mixing bowl. Add the hot cream mixture about 1/4 cup at a time to the beaten yolks, whisking well after each addition. Pour the mixture back into the saucepan and cook, stirring over medium heat until the mixture becomes thick enough to lightly coat the back of a spoon, 2 to 3 minutes, do not let it boil. Remove from the heat and strain through a fine-mesh strainer into a glass bowl. Cover the top of the mixture with plastic wrap (this will keep a skin from forming) and let cool. Place the mixture in the refrigerator and chill completely. Pour the mixture into an ice cream machine and follow the manufacturer's instructions for the churning time. Once the ice cream is almost ready, about 5 minutes before the churning time is complete, add the crumbled pralines through the ingredients spout. Continue to churn until the ice cream freezes. Line an 8 1/2 by 4 1/2 by 2 1/2-inch loaf pan with plastic wrap. Scoop the ice cream into the pan, smooth the top, cover, and freeze until firm, about 4 hours. When ready to assemble the ice cream sandwiches, lift the ice cream out with the plastic wrap.
Yield: about 1 quart.