- Line a large rimmed baking sheet with parchment paper. 
- To a medium, heavy-bottom saucepan over medium heat, add butter and sugar. Cook, stirring consistently with a wooden spoon until the candy reaches 285°F on a candy thermometer. (It should be a dark amber color.) This will take between 35-45 minutes; don't rush it. If your temperature is rising too quickly, turn the heat down slightly. 
- Pour the candy mixture onto an 11x15 lined baking sheet. While still hot, top with chocolate chips in an even layer. Let it rest for 1-2 minutes to allow the chocolate time to soften and melt. Carefully spread the chocolate into an even layer. 
- Sprinkle with pecans and gently press them into the melted chocolate. 
- Let it sit for about 1 hour, or until set. 
- To serve, break into pieces. 
- To store, place pieces in an airtight container at room temperature for up to a week.