Chocolate Truffles

12 ounces bittersweet chocolate, roughly chopped
1/2 cup heavy cream
2 tablespoons light corn syrup
1/2 teaspoon vanilla extract
1/4 teaspoon table salt
2 tablespoons unsalted butter, cut in to small pieces and softened
1/2 cup Dutch-processed cocoa
1/4 cup powdered sugar
Optional coatings **
1/2 cup roasted pistachios, chopped super fine
1/2 cup powdered sugar
1/2 cup crushed toffee bits (I used homemade toffee but you can use Heath bars)
Make a parchment sling for an 8-inch square baking dish by folding 2 long sheets of parchment so that they are as wide as baking dish.  Lay sheets of parchment in pan perpendicular to each other, with extra hanging over edges of pan.  Push parchment into corners and up sides of pan, smoothing flush to pan.
Microwave chocolate in medium bowl at 50% power, stirring occasionally, until mostly melted and few small chocolate pieces remain, 3 to 4 minutes; set aside.  Microwave heavy cream in measuring cup until warm to touch, about 30 seconds.  Stir corn syrup, vanilla extract and salt in to cream and pour mixture over chocolate.  Cover bowl with plastic wrap, set aside for 3 minutes, and then stir with wooden spoon to combine.  Stir in butter, one piece at a time, until fully incorporated.
Using rubber spatula, transfer ganache to prepared pan and set aside at room temperature for 2 hours.  Cover pan and transfer to refrigerate; chill for at least 2 hours.
For the coating, sift cocoa and powdered sugar twice over a large cake pan using a fine mesh strainer and set aside.
Gripping overhanging parchment, lift ganache from pan.  Cut ganache into sixty four 1-inch squares (8 rows by 8 rows).  Dust hands lightly with cocoa mixture to prevent ganache from sticking and roll each square into ball.  Drop balls in cake pan with cocoa mixture and roll evenly to coat.  Lightly shake truffles in hand over pan to remove excess coating.  Transfer coated truffles to airtight container and repeat until all ganache squares are rolled and coated.  Cover container and refrigerate for at least 2 hours or up to 1 week.  Let truffles sit at room temperature for 5-10 minutes before serving.
** If you want to use the optional coatings, after rolling ganache in to balls immediately coat them in the chopped pistachios, toffee bits or powdered sugar.  Don't roll them in cocoa first and then the other coatings!