Preheat oven to 350°F. In a medium bowl, whisk together flour, baking soda, baking powder and pumpkin spice pudding mix. Place the butter and brown sugar in a large bowl. With an electric mixer on medium speed, beat for 3 minutes. Then add eggs, one at time, followed by vanilla. Beat on medium for another minute.
Scrape down sides. Then reduce to low speed and add dry ingredients. Combine until just incorporated. Fold in 1 cup of the chocolate chips (reserving 1/2 cup of chips for the top of cookies).
Line a large baking sheet with a baking mat or parchment paper. Measure about 2 tablespoons of dough per cookie. Roll into a ball. Space the cookies 2 inches apart.
Slightly flatten the cookies using the palm of your hand. Place about 5 chips on top of each cookie. Bake for 8-10 minutes or just until set. DO NOT OVERBAKE! Let cool for 5 minutes before transferring to cooling rack.
Meanwhile, prepare the filling. Place butter in a large bowl and beat with an electric mixer on medium speed for 2 minutes. With mixer on low speed, gradually add half of the sugar and cocoa powder, then half of the cream. Beat on low until combined. Add the remaining sugar, cocoa and cream. Add vanilla. Beat on low until combined. Then turn speed up to medium high and beat for 2-3 minutes.
Frosting should be creamy and slightly shiny. If it's dull looking and too thick, add a little more cream. Try 1-2 more tablespoons, then beat again on medium for about 30 seconds. Repeat, if needed.
Fill cookies. I used a decorating bag fitted with a #1M tip. You can also just spread the filling with a spoon or spatula. Makes 10-12 sandwich cookies.