Ganache, the classic chocolate and cream preparation, is perfect for filling cookies. This version, with a little butter and corn syrup added, is particularly smooth.
In a small saucepan, combine the cream, butter, and corn syrup. Bring to a simmer over medium heat.
Remove from the heat and add the chocolate all at once. Shake the pan to make sure all the chocolate is submerged; let the chocolate melt for about 2 or 3 minutes. Whisk smooth, then scrape into a bowl and cool to room temperature, when the ganache will set and t