Make the Ice Cream Custard: Place a fine-mesh strainer over a large bowl; set aside. In a medium bowl, whisk the egg yolks briefly to break them up. Whisk in the malted milk powder (it will resemble a thick paste); set aside.
In a medium-sized heavy saucepan, stir together the heavy cream, milk, sugar and salt. Place over medium-high heat and warm until the mixture just begins to reach a simmer, then reduce the heat to medium.
Using a ladle, scoop out some of the cream mixture and whisk into the egg yolks. Repeat with another ladle-full of cream mixture, whisking constantly. Use a spatula to scrape the warmed egg mixture back into the saucepan.
Cook the mixture over medium heat, stirring constantly, until it is thickened and coats the back of the spatula, about 1 to 2 minutes longer. If you have an instant-read digital thermometer, the mixture should be between 170 and 175 degrees F.
Pour the mixture through the fine-mesh sieve into the bowl. Place the bowl in an ice bath and allow to cool completely. Cover and refrigerate for at least 4 hours, or overnight.
Make the Peanut Brittle: Line a large baking or cookie sheet with parchment paper; set aside.
Combine the sugar, water, corn syrup and salt in a small, heavy saucepan. Place the pan over medium heat and cook without stirring until the mixture reaches 280 degrees F, which may take as long as 20 to 25 minutes.
Once it reaches temperature, stir in the peanuts and stir frequently until the peanuts begin to smell toasted and the syrup is a mahogany color (about 5 minutes).
Remove from the heat and stir in the baking soda (it will bubble up) until thoroughly mixed in, then stir in the butter.
Pour the mixture onto the prepared baking sheet and, using a spatula, work quickly to spread the mixture into a thin, even layer. Allow the brittle to cool to room temperature (about 1 hour). Finely chop enough of it to measure ½ cup to use in the recipe; the remainder can be broken into large pieces and stored at room temperature in an airtight container for another use.
Churn the Ice Cream Custard: Add the vanilla extract to the custard base and stir until it is thoroughly blended in.
Freeze the ice cream in your ice cream maker according to the manufacturer's instructions. Once the ice is done churning, fold in the ½ cup of chopped peanut brittle and the milk chocolate chunks with a rubber spatula. Transfer the ice cream to a freezer-safe container and freeze for at least 4 hours.