1
: In one small saucepan, heat half a can of sweetened condensed milk with semi-sweet or dark chocolate and 1/4 tsp (1 mL) baking soda. Stir frequently until chocolate is melted. Stir in vanilla extract.
2
: In another small saucepan, heat remaining sweetened condensed milk with white chocolate, 1/4 tsp (1 mL) baking soda and peanut butter, stirring until melted.
3
: Pour dark chocolate mixture in parchment paper-lined 8" (20 cm) square pan. Pour peanut butter mixture on top and swirl with a spoon or knife. Cool. Chill 4 hours or until firm.
4
: Remove from pan and cut into 1" (2.5 cm) squares.