To Make the Ice Cream: Warm the milk, granulated sugar and salt in a medium saucepan over low heat, stirring occasionally, until the sugar is dissolved. Whisk together the cream, brown sugar and cinnamon in a large bowl and set a mesh strainer on top.
In a separate medium bowl, whisk together the egg yolks. Slowly pour the warm milk mixture into the egg yolks, whisking constantly, then scrape the warmed egg yolks back into the saucepan.
Stir the mixture constantly over medium heat with a heatproof spatula, scraping the bottom as you stir, until the mixture thickens and coats the spatula (it should reach between 170 and 175 degrees F on an instant-read thermometer). Pour the custard through the strainer and stir it into the cream. Mix in the vanilla and stir until cool over an ice bath. Cover and chill in the refrigerator overnight.
To Make the Oatmeal Praline: Preheat oven to 350 degrees F. Line a baking sheet with foil, spread the oats evenly on the sheet, and bake for 10 minutes, stirring once or twice while baking, until the oats are fragrant and nicely toasted. Remove from the oven.
Spread the sugar in a medium, heavy-bottomed skillet and cook over medium heat, watching it carefully. When it begins to liquefy and darken at the edges, use a heatproof spatula to stir it very gently, encouraging the heat of the liquefied sugar around the edges to moisten and melt the sugar crystals in the center.
Tilt the pan and stir gently until all the sugar is melted and the caramel begins to smoke. Once the mixture is deep golden, remove it from the heat and immediately add the oats to the skillet. Return the foil to the baking sheet.
Stir the oats gently but quickly, coating them with the caramel. Scrape the oats onto the foil-lined baking sheet and spread them as well as possible. Sprinkle with the salt and let cool completely. Once firm, break the pralined oats into small pieces (you can pulse in a food processor quickly, or put them in a plastic bag and hit them with a rolling pin).
Make the Raisins & Churn the Ice Cream: When you are ready to churn the ice cream, prepare the raisins. Heat the water and sugar in a small saucepan over low heat until the sugar is dissolved. Add the raisins and cook, stirring frequently, until all but about 2 tablespoons of the syrup has been absorbed, about 5 minutes. Remove from the heat and stir in the whiskey (you can omit the whiskey if you don't consume alcohol). Let cool while you churn the ice cream.
Churn the ice cream according to the manufacturer's instructions, adding the praline pieces and raisins during the last few minutes of churning. Transfer to a freezer-safe container and freeze.