Preheat oven to 350°F and prepare cookie sheets with parchment paper.
Using a stand mixer fitted with the paddle attachment, add the butter, sugar, and brown sugar to the bowl.
Cream the softened butter and sugars together on medium speed (speed 4 for a Kitchen Aid) for 2-4 minutes until light and fluffy.
Scrape down the sides of the bowl and add the peanut butter. Mix on a medium speed until combined.
Next, scrape down the sides of the bowl and add one egg at a time mixing until fully combined and scraping down the sides of the bowl after each egg. Then add the vanilla and mix until combined.
In a separate bowl, measure the flour, salt, and baking soda.
Add the dry ingredients to the mixing bowl and mix on a low speed until the flour is almost completely mixed in.
Finally, add the semi-sweet chocolate chips and mini peanut butter cups. Continue mixing on low until the chocolate chips and peanut butter cups are evenly distributed. Be careful NOT to overmix!
Using a cookie scoop, scoop the cookie dough and place 1 inch apart from each other on the parchment lined cookie sheets. If desired, sprinkle sea salt flakes on top of the cookie dough balls before baking to create a sweet and salty flavor.
Place the trays in the oven and bake for 10-12 minutes or until the edges are slightly golden brown.
Allow cookies to slightly cool and enjoy!