In a medium bowl mix together flour, salt, and baking soda..
In a separate large mixing bowl beat the butter and sugars together with an electric mixer until well blended.
Add the egg, egg yolk, and vanilla. Stir in the dry ingredients and mix until just combined.
Gently stir in ¾ cup chocolate chips. The dough will be soft.
Gently scoop dough into balls and place on a parchment lined cookie sheet. Bake for 10-12 minutes.
Remove from oven and place 3-4 chocolate chips into the tops of each cookie, point side up.
Add remaining chocolate chips to a microwave safe bowl and microwave, on low power, stirring every 30 seconds, until melted.
Just barely cut the corner off of a small ziplock bag (you want the hole to be very small to make your spider legs). Spoon the melted chocolate into the bag and use it draw spider legs on the sides of the chocolate chips.
Store cookies in an airtight container or freeze in a freezer ziplock bag.