Prep the apples: Wash apples thoroughly to remove any waxy coating. Dry completely. Remove stems and insert wooden sticks firmly into the tops. Line a baking sheet with parchment paper and lightly spray with nonstick spray.
Make the candy syrup: In a heavy-bottomed saucepan, combine sugar, corn syrup, and water. Heat over medium-high, stirring occasionally until sugar is fully dissolved.
Cook to hard crack stage: Attach a candy thermometer to the side of the pot. Bring the mixture to a boil and cook without stirring until it reaches 300°F (149°C)—this is the hard crack stage. Be patient and do not stir during this phase.
Color and flavor: Remove the pot from heat. Quickly and carefully stir in the black gel food coloring and vanilla extract. Mix gently until fully incorporated and the syrup is a deep, glossy black.
Dip the apples: Working swiftly, dip each apple into the hot candy syrup. Rotate to fully coat and allow excess to drip off. Place each apple on the prepared parchment-lined baking sheet.
Let set: Allow the apples to cool and harden at room temperature for about 20–30 minutes. Do not refrigerate, as it may cause the candy to sweat or soften.
