1. Line an 8-inch square pan with parchment paper, leaving overhang on two sides.

2. Add semisweet chocolate chips, sweetened condensed milk, butter, and salt to a saucepan.

3. Warm over low heat, stirring often, until melted, glossy, and smooth.

4. Remove from the heat and stir in vanilla extract and peppermint extract.

5. Spread the chocolate fudge mixture evenly into the prepared pan.

6. Melt the white chocolate chips gently in the microwave in short bursts, stirring between each one.

7. Spoon the melted white chocolate over the fudge and swirl with a toothpick or thin knife.

8. Sprinkle crushed peppermint candies over the top and press lightly so they stick.

9. Refrigerate for at least 2 hours, or until firm.

10. Lift the fudge from the pan, slice into small squares, and serve chilled or at cool room temperature.