Preheat the oven to 375 F. Line 2 baking sheets with parchment paper.
Place the butter and sugars in a stand mixer fitted with a paddle attachment. Beat on medium-high speed until light and fluffy, 3 to 4 minutes.
Add egg and vanilla, mix until smooth on low speed.
Slowly mix in dry ingredients, being careful not to over mix. I usually stop when I still have some flour remnants around the bowl.
Add chocolate chips and break up your ice cream cone into little pieces and stir. Place 3 scoops of hot fudge about a tablespoon each onto the dough and swirl in. Don't stir too much or you'll lose the marbling affect.
Scoop the dough into desired size cookie balls. I like to use a 4 tablespoon scoop for these.
Place 5-6 cookie balls on the baking sheet and sprinkle with flaked salt. Bake for 11-14 minutes, or until the edges start to turn golden brown. Run a spoon or spatula around the freshly baked cookies to help shape a perfect circle. Top with more salt if desired.
Notes
Make sure your hot fudge is very cold or it will get too runny when baking. You can scoop 3 different tablespoons onto a plate and place in the freezer for 15 minutes to make sure it's extra cold if you want.The butter and eggs should not be completely chilled from the fridge, but should also not be room temperature. I try to let them sit out for about 15-30 minutes before I begin my cookie making!I have given both cups and grams as measurements. Grams will be more precise, especially when measuring flour. If you don’t have a kitchen scale, no problem! Just lightly spoon flour into your measuring cup to insure its not packed in there. Light and fluffy is the key.