Preheat oven to 350 degrees. Line 2 baking sheets with parchment and set aside.

In a food processor, puree 3/4 cup Cap'n Crunch until fine. In a medium bowl, whisk together powdered Cap'n Crunch, flour, baking soda, and salt. Set aside.

In a large bowl, cream together butter, sugar, and brown sugar until light and fluffy. Add egg and vanilla, stirring to combine. Beat in flour mixture until a soft dough forms. Fold in remaining 3/4 cup Cap'n Crunch.

Roll 1 heaping tablespoon of dough into a ball and place on prepared baking sheet, leaving room for spreading. Continue with rest of dough. Bake for 10-12 minutes or until lightly browned around edges. Remove from oven and let rest for 5 minutes on baking sheet. Transfer to wire rack and let cool completely. Serve immediately or store in an airtight container.