STEP 1: Prepare oven and baking pan. Heat the oven to 162°C. Line a 13 x 9-inch baking pan with aluminium foil or parchment paper.
STEP 2: Add crackers to the baking pan. Arrange the crackers in a single layer on the pan.
STEP 3: Make toffee mixture. Cook the butter and brown sugar in a small saucepan over medium-low heat until melted and smooth, stirring slowly. When it begins to bubble, cook for 3 minutes while stirring.
STEP 4: Add toffee mixture to crackers and bake. Pour slowly and evenly over the crackers. The crackers might float a little; just move them back in place with the tip of a knife and make sure all of the crackers are covered in the sugar mixture. Bake 15 minutes.
STEP 5: Add chocolate chips. Remove pan from the oven, and sprinkle chocolate morsels evenly over the top. Return to the oven until the chips begin to melt and lose their shape, about 1 minute. Spread the melted chocolate evenly over the surface and sprinkle with pecans.
STEP 6: Cool until firm. Let stand until nearly set, and then chill in the fridge until firm, at least 2 hours. Break into pieces. Store refrigerated in an airtight container.