Spread out peanuts in a single layer on a sheet pan and toast in oven for 16 to 18 minutes until golden brown.
Let cool, then coarsely chop.
Combine flour, baking soda, and baking powder in a medium bowl and whisk together. Set aside.
Combine butter and peanut butter in bowl of stand mixer. Beat on medium low speed until combined and has the consistency of mayonnaise and holds a peak when the paddle is lifted.
Add brown sugar and beat for 2 minutes until fluffy. Scrape down sides of bowl.
Add egg and vanilla paste and beat just until combined. Scrape down sides of bowl.
Add in flour mixture in 2 additions, beating just until combined.
Add oats and mix to combine.
Add in chopped peanuts and mix to combine.Turn out dough onto a piece of plastic wrap and form into 5" x 7" block. Wrap tightly and refrigerate until firm, at least 2 hours.
Roll out dough between two pieces of parchment paper or Silpats to 1/4" thick. The dough will soften very quickly so if it starts getting too soft and sticky put back in refrigerator to firm up slightly before continuing to roll.Using a 3 1/4" round cutter, cut out cookies from the dough and place on baking sheets lined with parchment paper. Wrap sheets in plastic wrap and freeze for at least 2 hours until firm. You can also store the dough frozen for up to 1 month.Preheat oven to 325 degrees F. Arrange frozen cookies on baking sheets lined with parchment paper or Silpats about 2 inches apart.
Bake for 16 to 18 minutes, rotating pans halfway through, until they are golden brown at the edges.
Remove and let cool. For the filling:Cream together all ingredients in a stand mixer until very smooth.To assemble:Scoop filling into a pastry bag fitted with an Ateco #867 star tip (opening size approx. 9/16" if you have other tips). Pipe a spiral of filling on half the cookies, starting at the center and working out to within 1/4" of the edge.Top each with a second cookies and press gently down.
