For the ice cream, mix and heat half the cream (1c or 240ml 0r 245g), the milk, sugar, toasted milk powder, and salt in a saucepan until all of the sugar has dissolved. Whisk in the vanilla bean paste, turn off the heat, and let the mixture sit until its temperature comes down to 140°F (60°C).
In a separate bowl, whisk the eggs yolks until they froth and lighten in color slightly. Then, slowly temper the cream mixture into the egg yolks by ladling a small stream of cream into the eggs while whisking constantly, until all of the cream mixture is combined.
Scrape the fully combined mixture back into the saucepan and stir it constantly over medium-low heat with a heatproof spatula until mixture thickens and coats the spatula. Make sure to check the temperature while you heat the custard. Do not go over 180°F (82°C) while thickening. I tend to keep mine between 170-175°F (76-79°C) to be on the safe side.
If you are really worried about overcooking your custard, you can always use a double boiler as a safety net. (See FAQs) You'll know the custard is done when you can run your finger across the coated spatula and the custard doesn't run back together.
Add the remaining cup of cream to a large bowl and set a fine mesh strainer on top. Then, pour the thickened custard into the strainer and use a spoon to stir and scrape it through the mesh and into the bowl below.
Next, add the bourbon to the custard mixture and stir everything together. Cover the container and chill the mixture completely in the refrigerator. It should take roughly 4-8 hours. (see notes for a chilling shortcut)
When the ice cream base is ready to churn, pour the mixture into an ice cream maker and freeze according to the manufacturer's instructions. Once the browned butter bourbon ice cream is partially frozen into a soft serve consistency, scrape it out of the mixer and into a freezer safe container. Freeze for at least another 4 hours or overnight for best results. Scoop and enjoy!