Heat oven to 425 degrees F.
Line a 15- x 10-inch jelly roll pan with heavy duty foil. In a medium saucepan melt ¼ cup butter and pour into the prepared pan. Tilt the pan as needed to spread the melted butter out in an even layer to coat all of the foil. Arrange the crackers over the butter.
Melt remaining butter in the same saucepan and stir in the brown sugar. Bring to a boil over MEDIUM heat. Reduce heat and cook for 2 to 3 minutes, stirring occasionally.
Remove the pan from the heat and stir in the sweetened condensed milk. Mix well. Spread the toffee mixture evenly over the crackers.
Bake for 9 to 10 minutes until mixture is bubbly and golden brown. Carefully remove the pan from the oven.
Immediately sprinkle with the chocolate morsels and let stand 5 minutes until the chocolate has melted. Spread the chocolate with an offset spatula or butter knife into an even layer. Sprinkle with the nuts and lightly press them into the melted chocolate. Allow to cool on your kitchen counter in the pan for 30 minutes and then refrigerate until the chocolate is set, an additional 30 to 60 minutes.
Lift the foil to remove the entire sheet of candy from the pan. Carefully peel off and remove the foil. Use a sharp knife to cut the candy into squares.
Store the toffee candy in an airtight container in the refrigerator for up to 2 weeks. It's delicious served chilled but can also be served at room temperature.