This recipe is a miracle of science: add a little baking soda to a dark, maple caramel and soon you have this impossibly crunchy, airy candy. I sprinkle the candy with sea salt to cut the sweetness. —Merrill Stubbs
Line a baking sheet with a Silpat mat or some greased parchment.
Combine the sugar and maple syrup with 1/4 cup cold water in a medium, heavy saucepan. Set over medium high heat, stirring just until the sugar dissolves. (After this point, do not stir -- you can swirl the pan occasionally if you'd like.) Let the mixture come to a boil and cook until it reaches nearly 300 degrees and is a dark amber color (this should take 5 to 7 minutes).
Working quickly, remove the pan from the heat and whisk in the baking soda, just enough to mix the two thoroughly. Immediately pour the mixture onto the lined baking sheet, using a heatproof spatula to scrape it from the pan. It will be tempting, but do not smooth the mixture -- you'll get rid of all those air bubbles!
Quickly sprinkle the surface of the candy evenly with the sea salt. Set the baking sheet in a cool, dry place and let the candy cool. When it is hard, break it apart into uneven chunks with your fingers. Note: Dip the candy pieces in melted semisweet chocolate and let them cool again for an even richer treat.