Heat the mixture. In a saucepan over medium heat, combine the milk, cream, ½ cup of sugar, and vanilla bean. Heat until warm and steaming, around 170°F.
Prepare the egg mixture. In a separate bowl, whisk together the egg yolks and the remaining ¼ cup of sugar until they turn light yellow and blend well. You can use a hand mixer on low speed for this.
Temper the eggs. Slowly add half of the warm milk mixture to the egg mixture, a half cup at a time, whisking continuously to prevent the eggs from curdling. Then, pour the egg mixture back into the saucepan with the remaining milk and cream.
Cook the custard. Cook the mixture over medium heat, stirring constantly, until it reaches 185°F. Be careful, don't let it boil. Take it off the heat, add a little salt, and mix in the vanilla extract if you're using it.
Strain and chill. Strain the custard through cheesecloth or a fine-mesh strainer, then place it immediately in the refrigerator to chill. Return the vanilla bean to the custard. Chill for 4-24 hours, until very cold.
Churn the ice cream. Pour the chilled custard into your ice cream maker and churn according to the manufacturer's instructions, usually about 20-25 minutes, until it reaches the consistency of soft serve.
Freeze the ice cream. Freeze the custard according to your ice cream maker's instructions. When it reaches the consistency of soft serve, transfer it to a loaf pan, cover with plastic wrap, and place in the freezer until firm. Also, refrigerate the caramel and fudge sauces to firm up.
Add the swirls. Remove the vanilla ice cream from the freezer. Pour the caramel and fudge sauces on top, and gently stir with a butter knife to create swirls throughout. Place back in the freezer for at least 1 hour to firm up.
Serve. Allow the ice cream to soften at room temperature for 10 minutes before serving. It will keep well in the freezer for up to 1 week.