Line a loaf pan with parchment paper. Set aside.
Measure maple syrup into a heavy duty saucepan with a candy thermometer on the side, and bring to a boil over medium-high heat.
Lower temperature and simmer 5 minutes. If syrup starts to rise, lift pan and swirl contents to prevent scorching.
Add heavy cream without stirring, and raise heat again to medium-high, and bring back to a boil.
Simmer until temperature reaches 248 degrees, or firm ball stage.
Remove from heat, add butter without stirring. Cool 10 minutes.
Transfer mixture to a stand mixer, and beat on medium speed until sheen just starts to go away (as mixture turns from shiny to dull).
Stir in pecans.
Pour in prepared loaf pan, and allow to cool for 2 hours, then cut into squares.
