01 -
Preheat oven to 350°F (175°C). Line a muffin tin with paper liners to prevent sticking and make removal easier.
02 -
In a large bowl, cream together softened butter, brown sugar, and granulated sugar until light and fluffy. Mix in egg (if using) and vanilla extract until well combined. Gradually add flour and mix until a soft dough forms.
03 -
In a separate bowl, beat together peanut butter and powdered sugar until smooth. Roll this mixture into 24-30 small balls and place in refrigerator to chill for about 10 minutes.
04 -
Press a portion of cookie dough into each muffin cup, creating a small well in the center. Place a chilled peanut butter ball in each well. Top with chocolate chips and optional add-ins. Add a small amount of remaining dough on top to partially cover.
05 -
Brush the tops of each cookie bite with egg yolk wash for a beautiful golden finish.
06 -
Bake for 12-15 minutes, or until edges are lightly golden brown and centers are just set.
07 -
Allow cookie bites to cool in the muffin tin for about 5 minutes before transferring to a wire rack. The peanut butter center will be gooey when warm and set more as they cool.