In a large microwave-safe bowl, heat the butter until just melted. Be careful not to overheat it; you want it soft and melty, not bubbling. Once melted, let it cool slightly before adding the next ingredients.
Stir in the peanut butter, brown sugar, baking soda, and salt. Mix well until everything is combined and smooth. The mixture should look creamy and inviting.
Whisk in the eggs and a touch of vanilla extract until fully incorporated. You’ll want to ensure there aren’t any lumps, making it nice and velvety.
Now, it's time to mix in the oats. Stir until they’re well combined into the mixture. This will give the cookies that hearty texture we all love.
Gradually add the white whole wheat flour and all-purpose flour, mixing gently until just combined. Be careful not to overmix, as this can lead to tough cookies.
Finally, fold in the chocolate chips and mini peanut butter cups. This is where the magic happens! Each bite will be filled with melty chocolate and creamy peanut butter.
Cover the bowl with plastic wrap and refrigerate for about an hour. This step is important as it helps the dough firm up, which will result in thicker cookies.
Preheat your oven to 350 degrees F (175 degrees C) while you wait. Line your baking sheets with parchment paper to prevent sticking.
Scoop out heaping tablespoons of the cookie dough or use a 2-inch cookie scoop to form balls. Place them on the prepared cookie sheets about 2 inches apart. Utilize the bottom of a drinking glass to gently press down each ball a little.
If you desire, press additional chocolate chips into the tops of the cookies before baking. This will give them a pretty look and extra chocolatey goodness.
Bake in the preheated oven for 11 to 14 minutes or until the cookies are slightly firm to the touch in the center. They should be very lightly golden around the edges.
Once baked, carefully transfer the cookies to a wire rack to cool completely. They will continue to firm up as they cool, so don’t worry if they seem a bit soft right out of the oven.
Store any leftovers in a covered container for up to a week. If you want to save them for later, you can freeze the cookies for up to four weeks. Just make sure to wrap them well!
