In a saucepan over medium heat, mix the Sugar, Milk, Salt and Corn Syrup, stirring constantly until the sugar has dissolved.
Now stirring occasionally, cook until temperature reaches 240F on a candy thermometer, (If you don't have a thermometer, you can test to see if it's ready by dropping a small amount of the candy into cold water and if it forms a small ball, and then flattens out once you remove it from the water.)
Remove from heat.
Add in the butter to the hot mixture and stir until the temperature now reaches 120F. (Pan on bottom will be lukewarm).
Now add in the ground Cardamom.
Keep stirring until the candy fudge starts to thicken.
After about 3 minutes of stirring add in the chopped Pistachios and Walnuts. Continue to stir another 5 minutes. Mixture will start to hold it's shape.
In a well buttered dish (I used a 9x5 loaf pan), spread the mixture evenly.
Gently press whole Pistachios evenly across the top of fudge, so that when cut each piece will have one nut centered on top.
Set aside until firm, (I usually wait about 45 min - 1 hr.)
Cut into small 1 inch squares.
Can be kept in an airtight container for up to a week.
Makes about 20 - 24 Squares.