In a large bowl, whisk together the sweetened condensed milk, nonfat milk powder, vodka, and salt until well combined. Set aside.
Add the heavy cream to another large bowl, then use a hand mixer or stand mixer fitted with the whisk attachment to whip the cream on medium-high speed until stiff peaks form.
Add around ⅓ of the whipped cream to the sweetened condensed milk and lightly stir to lighten the mixture.
Add in the rest of the whipped cream, then gently fold to combine until there are no streaks of condensed milk left. If adding mix-ins, fold them in at the end until just combined.
Pour the mixture into a 9x5 loaf pan, then use a rubber spatula to smooth the surface. Sprinkle over any additional toppings, if desired, then cover the pan with plastic wrap, gently pressing it to the surface of the ice cream.
Place the loaf pan into the freezer and chill for at least 6 hours (preferably overnight) before scooping and serving.