Preparation

• Step 1 Preheat oven to 350°.
• Step 2 Put pecans on a rimmed baking sheet and cook, stirring occasionally, until toasted, about 8 minutes.
• Step 3 When cool enough to handle, chop roughly.
• Step 4 Divide into 2 batches; chop 1 batch finely.
• Step 5 Set both batches aside.
• Step 6 Put sugar, butter, salt, and 3/4 cup water in a 4-qt.
• Step 7 saucepan over medium heat.
• Step 8 When butter and sugar are melted, increase heat to medium-high and cook, stirring occasionally, until mixture is deep golden brown and measures 310° on a candy thermometer, about 20 minutes.
• Step 9 Remove from heat and carefully stir in vanilla (mixture will bubble up) and finely chopped pecans.
• Step 10 Pour into a 10- by 15-in.
• Step 11 rimmed baking sheet.
• Step 12 Let toffee cool until set, at least 30 minutes. (For even pieces, you can "score" the toffee by cutting it with a sharp knife after it has set for about 10 minutes, scoring into 5 strips lengthwise and 8 strips crosswise to yield 40 pieces.
• Step 13 Wipe knife clean with warm water after each slice for easier cutting.)
• Step 14 Chop chocolate and put in a medium metal bowl.
• Step 15 Fill an 8- or 10-in.
• Step 16 frying pan with 1/2 in.
• Step 17 of water and bring to a boil.
• Step 18 Take off heat and put bowl of chocolate in the water.
• Step 19 Let sit about 5 minutes.
• Step 20 Stir chocolate until melted.
• Step 21 Pour over toffee; with a knife or offset spatula, spread evenly.
• Step 22 Sprinkle chocolate with roughly chopped pecans.
• Step 23 Let sit 20 minutes, or until chocolate is cool but still a bit soft.
• Step 24 Sprinkle with kosher salt.
• Step 25 Chill.
• Step 26 To remove, gently twist pan to release toffee, then chop or break into chunks.
• Step 27 Store.