OLD-TIME BITTERSWEET HOT FUDGE

10 ounces bittersweet chocolate (Lindt Excellence 70%, Valrhona 71%, Scharffen Berger 70%, or Ghirardelli 70% Extra Bittersweet, in order of our preference)
1 ounce unsweetened chocolate
2 tablespoons unsalted butter
½ cup heavy whipping cream, plus 2 tablespoons extra if needed
6 tablespoons light corn syrup
1 teaspoon vanilla extract

It is as necessary to a kitchen as garlic.

Combine the two chocolates and the butter in a small microwave-safe bowl. Begin melting them in a microwave oven set at medium-low power for 2 to 3 minutes. Check how the melting is progressing by stirring often. Chocolate holds its shape when microwaved, so it can be deceiving. When the chocolate is fully melted, set it aside. Alternatively, melt the chocolates and butter in a bowl set over simmering water. When melted, remove the bowl from the water and cool for 5 minutes.
In a 2-quart saucepan, stir together the ½ cup cream, the corn syrup, and the vanilla. Stir as you bring them to a simmer over medium-high heat. Remove the pan from the burner and cool for 2 minutes. Whisk in the chocolate-butter blend until smooth. If the sauce is too thick, add the remaining 2 tablespoons cream.
Serve the hot fudge immediately, or rewarm it in bowl over simmering water to preserve the silky consistency.