Combine milk, coffee beans, and ½ cup (120 mL) cream in a large saucepan. Cover and remove from heat once the mixture is steaming considerably, just before it starts to boil. If using brewed coffee instead of whole beans, do not include it at this stage. Leave the saucepan covered at room temperature to give the coffee beans time to lend flavor to the milk. Skip this step if using brewed coffee instead. Whisk for about 5 minutes, or until it turns pale yellow and falls off the whisk in thick ribbons. Return the saucepan to the stove and reheat until once again hot and steaming. Pour very slowly into the egg mixture, whisking constantly.  Pouring too fast here will cook the egg, which is taking ice cream breakfast ingredients a step too far. If you notice any lumps, stop pouring and beat the mixture vigorously.  If the beans are getting in the way of stirring, pour through a mesh and return the beans to the mixture once you're done whisking. Pour the remaining cup (240 mL) heavy cream into a metal bowl. Place this bowl inside a larger container, filled with ice. Return the egg and milk mixture to the saucepan. Heat on medium low, stirring constantly with a flat-bottomed spatula. Cook until you can run your finger on the spatula without the custard running across the mark you made. If you're not used to making custard, consider the following safeguards:  Use an infrared thermometer to make sure the temperature stays below 180ºF (82ºC). To avoid burning the bottom or heating it too quickly, use a double boiler. Place a mesh strainer over your chilled cream, to catch the coffee beans. Pour the hot custard through this strainer. Press the beans to extract flavorful liquids, then discard them. Add vanilla extract to the ice cream and stir to combine. Chill the mixture in the refrigerator, then freeze in the ice cream maker according to your model's instructions. This typically takes less than half an hour. If substituting chilled, brewed coffee for whole beans, pour it in halfway through churning.

Summary:
Heat milk, coffee beans, and some of the cream. Let steep one hour. Whisk together egg yolks, sugar, and salt. Reheat milk mixture and whisk slowly into eggs. Place the remaining cream in an ice bath. Heat your custard base. Strain into the chilled cream and vanilla extract. Finish in the ice cream maker.