Place assorted nuts into a large bowl, set aside.
In a medium pot, combine the milk, sugar, salt and pumpkin pie spice and place over medium heat. Stir constantly for about 5 minutes until the sugar dissolves. Allow the mixture to come to a boil until it reaches at least 235°F but no more than 245°F.
Tip: If you do not have a candy thermometer, a great way to determine if you've reached this temperature range is to drop a spoonful of hot syrup into a bowl of very cold water. In the water, use your fingers to gather the cooled syrup into a ball. If it has reached soft-ball stage, the syrup easily forms a ball while in the cold water, but flattens once removed from the water—now you know!
Remove pot from heat, add vanilla extract, stir and pour over the bowl of mixed nuts. Using a wooden or silicone spatula, coat the nuts and lay on a flat surface covered with parchment or wax paper to cool. Once cooled, break apart and enjoy! Use as a topping on a salad, add to a fruit and cheese plate or simply eat by the handful.