Preheat the Oven:
Preheat your oven to 350°F (175°C). Line your baking sheets with parchment paper or silicone baking mats.
Mix Wet Ingredients:
In a large bowl, cream together the softened butter, peanut butter, granulated sugar, and brown sugar until light and fluffy. This should take about 2-3 minutes using a hand mixer or stand mixer on medium speed.
Add in the eggs, one at a time, mixing well after each addition.
Combine Dry Ingredients:
In a separate bowl, whisk together the flour, baking soda, and salt. Gradually add the dry ingredients to the wet mixture, mixing until fully incorporated.
Add Chocolate and Peanut Butter Chips:
Stir in the chocolate chips and peanut butter chips (if using). The dough should be thick and slightly sticky.
Shape the Dough:
Use a spoon or cookie scoop to portion out the dough into small balls (about 1 tablespoon each). Roll the dough balls between your hands to smooth them out, and place them on the prepared baking sheets about 2 inches apart.
Bake the Cookies:
Bake in the preheated oven for 8-10 minutes, or until the edges are golden brown and the centers are slightly soft. The cookies will continue to cook on the baking sheet once removed from the oven, so be careful not to overbake them.
Cool and Serve:
Remove the cookies from the oven and let them cool on the baking sheets for 5 minutes before transferring them to a wire rack to cool completely.
Optional Topping:
Once the cookies have cooled slightly, sprinkle a pinch of sea salt on top of each cookie for a sweet-salty finish.