Combine butter and sugars in the bowl of a stand mixer and beat until well combined (about 1 minute).
1 ¼ cup unsalted butter, 1 ½ cup light brown sugar, ¼ cup sugar
Add peanut butter, stir well.
1 cup creamy peanut butter
Add eggs and egg yolk, one at a time, pausing to scrape down the sides and bottom of the bowl after each addition.
2 eggs + 1 egg yolk
Stir in vanilla extract.
1 teaspoon vanilla extract
In a separate, medium-sized bowl, whisk together flour, baking soda, and salt.
3 cups all-purpose flour, 1 ½ teaspoons baking soda, 1 ½ teaspoon salt
Gradually add flour mixture into the peanut butter batter, pausing occasionally to scrape down sides and bottom of bowl so that all ingredients are well-combined.
Stir in chocolate chips.
1 cup milk chocolate chips, ¾ cup semisweet chocolate chips
Place your dough in refrigerator and chill for 30 minutes to one hour (start with 30 minutes, if the dough is too sticky or cookies come out too flat, return for another half an hour).
Preheat oven to 375F (190C) and line cookie sheets with parchment paper. Pour remaining ½ cup of sugar into a small bowl and set aside.
Once dough has chilled, remove from refrigerator and roll into approximately 2-Tablespoon-sized balls. Roll through sugar and place on prepared cookie sheet at least 2" apart.
½ cup granulated sugar
Bake on 375F (190C) for 10 minutes, remove from oven and allow to cool on cookie sheet for 10 minutes before removing to cooling rack to cool completely.