In a medium saucepan, bring the sugar and maple syrup to a boil. Swirl every 30 seconds or so until mixture reaches a dark amber color, about 7 minutes.
Quickly remove from heat and whisk in baking soda. Mixture will bubble up violently. Pour onto prepared pan and allow to cool completely.
Break the hardened maple honeycomb using a hammer or the back of a pot.
Make the ice cream
In a mixing bowl, whip the heavy cream until soft peaks form. Fold in the vanilla extract and salt, and continue to beat until the mixture holds soft peaks, about 30 seconds more.
Pour in the sweetened condensed milk and maple syrup. Whip until everything comes together, slightly past soft peak stage (ideally at medium peak. Is that a thing? Making it a thing).
Carefully spoon in 3/4 of the crushed maple honeycomb, then scoop the ice cream into a metal bread pan or other freezer-safe container. Top with last 1/4 of maple honeycomb.