Combine the cream, corn syrup, and butter in a small saucepan over medium heat; bring to a boil.

Add 8 ounces of chocolate; gently swirl the pan.

Allow to sit for 5 minutes.

Whisk to combine.

Transfer to a small mixing bowl, and refrigerate for 15 minutes.

Stir mixture, return to refrigerator for 2 more 15 minute periods, stirring after each for a total of 45 minutes.

At this point, the mixture will begin to harden more quickly, so the mixture should be stirred every 5 minutes.

When mixture is thicker but not hard, remove from refrigerator.*

Line a baking sheet with parchment paper.

Using a teaspoon, scrape a small amount of mixture from the bowl.

Using hands roll into a ball approximately 1 inch in diameter; place on parchment paper.

Repeat until all mixture is used.

Place baking sheet in refrigerator for 15 minutes.

Place remaining 4 ounces of chocolate in a small bowl and microwave in 30 second increments, stirring after each, until melted.

Pour sprinkles into a small bowl.

After 15 minutes, remove baking sheet from refrigerator. Place individual ball in melted chocolate and roll until fully coated.

Using a fork transfer to sprinkles bowl.

With clean hand, roll ball in sprinkles; return to baking sheet.

Repeat with remaining balls, and refrigerate for 10 minutes to set.