Line two baking sheets with parchment paper.
Melt 4 tablespoon butter in a medium saucepan over low heat. Once melted, add the oats. Cook oats in butter for about 5-7 minutes, stirring gently, until the oats are browned and toasted. Pour oats onto a sheet of parchment paper to cool a bit.
In a medium bowl, whisk together the flour, baking soda, and salt. Set aside.
In the bowl of a stand mixer or in a large bowl with a hand mixer, cream together remaining stick of butter and both kinds of sugar until light and fluffy, 2-3 minutes.
Add the peanut butter and beat together until well combined.
Slowly add in the flour mixture until just combined, taking care not to over-mix. Fold in the oats and peanut butter chips.
Place dough on a large sheet of parchment paper and place another large sheet of parchment paper on top. Roll the dough out until it’s about ¼-inch thick. Place in the fridge for 30 minutes to chill.
Preheat oven to 350 degrees.
Place dough on counter and remove top layer of parchment paper. Cut 24 circles out of the dough with a 2-inch round cookie or biscuit cutter (or the top of a drinking glass).
Place rounds about one inch apart on parchment paper-lined baking sheets. Bake for about 10 minutes, until cookies are just starting to turn golden.
Remove from oven, let cool for a few minutes on cookie sheet, and then move to a wire rack to cool completely.
Put raspberry jelly buttercream in a pastry bag or in a ziplock bag with the corner cut off and squeeze buttercream in a circular motion on 12 of the cookies. Top each cookie with a second bare cookie to make sandwiches.