1) Line an 8? x 8? pan with parchment paper or aluminum foil, and spray lightly with non-stick baking spray.
2) Place 1/2 cup cream in a medium saucepan. Add the espresso powder, corn syrup, salt, and sugar. Stir over medium heat until the espresso powder and sugar are dissolved and the mixture begins to boil.
3) Cover the pan and let boil for 3 minutes. Uncover the pan, and check the temperature; it should be 235°F to 240°F (soft ball stage). If it is, remove from the heat; otherwise let it boil for a minute or two more.
4) Once the mixture reaches 235°F to 240°F, add the vanilla. Be careful; it will splash and splutter when it hits the hot liquid. Set the mixture aside for about 10 minutes to cool.
5) Meanwhile, place the remaining 1/2 cup cream into a saucepan. Heat until it?s just beginning to steam.
6) Remove from the heat, and add the white chocolate. Let sit for about 5 minutes to melt. Then whisk vigorously until the mixture is shiny and smooth.
7) Add the sugar mixture to the chocolate mixture; stir to combine.
8) Combine the cocoa and ½ teaspoon espresso, and sprinkle the chocolate with some of the mixture.
9) Refrigerate for at least 4 hours, to set.
10) Turn the chocolate out of the pan and flip it over; sprinkle with the remaining cocoa/espresso powder blend.
11) Cut into 1? cubes. Stack two or three on a wooden stick. Roll in cocoa, or whatever you sprinkled on the top and bottom. Wrap in waxed paper, parchment or plastic wrap to store.
Yield about 64 blocks, 21 servings.