Place chocolate in a medium-size heatproof bowl. Bring cream and corn syrup just to a simmer in a small saucepan over medium-high heat; pour mixture over chocolate. Let stand, without stirring, until chocolate begins to melt.
Using a flexible spatula, gently stir chocolate and cream until totally combined; begin near the center of the bowl and gradually work your way toward the edge, pulling in as much chocolate as possible, until the mixture is smooth and glossy. (If any chocolate pieces remain, strain mixture through a fine sieve and discard solids.) If not using immediately, glaze can be refrigerated up to 5 days in an airtight container.
Reheat gently before using.
Shiny chocolate glaze variation: Reduce amount of chocolate to 2 ounces. Follow step 1 of recipe above, letting mixture stand 5 minutes before slowly whisking until smooth and combined. Use immediately, without straining.
Avoid overmixing when stirring the chocolate into the hot-cream mixture, as this can cause the ganache to become dull and grainy.