Pour the popcorn and slivered almonds into the buttered bowl.
In a medium pan, melt butter. Add the maple syrup and a dash of salt. Over medium heat, bring to a boil. Lower the heat and keep at a soft boil until a candy thermometer reads 300°F (about 15 minutes). Stir constantly.
Pour the maple syrup over the popcorn & slivered almonds and mix very well.
Spread the popcorn mixture onto the parchment paper. Let cool completely. Break apart and store in a covered bowl for 4 or 5 days.