1 cup (8 ounces) unsalted butter, at room temperature
1 cup creamy peanut butter, at room temperature
2 teaspoons pure vanilla extract
1 and 1/2 cups light brown sugar, packed
1/2 cup granulated sugar
2 large eggs, at room temperature
2 Tablespoons milk
1 and 3/4 cups all-purpose flour
1 teaspoon baking soda
1/2 teaspoon salt (kosher or table salt)
2 and 1/2 cups old fashioned oats
12 ounces chocolate chips
Preheat oven to 350 (F). Line two large baking sheets with parchment paper; set aside.
In the bowl of a stand mixer fitted with the paddle attachment, or in a large bowl using a handheld electric mixer, beat the butter on medium speed until smooth. Add in the peanut butter and vanilla and beat until smooth; about 2 minutes. Add in both sugars and beat until light and fluffy, about 3 minutes.
Beat in the eggs, one at a time, scraping down the sides as needed. Beat in the milk until it’s combined.
In a medium bowl, stir together the flour, baking soda, and salt.
On low speed, gradually beat the flour mixture into the wet ingredient mixture, beating until just incorporated. Turn mixer off. Beat in the oats and chocolate chips, mixing just until combined.
Scoop 2-inch balls of cookie dough onto the prepared baking sheets, leaving about 1 and 1/2 inches between so they have room to spread.
Bake, one sheet at a time, in preheated oven for 12 minutes, or until cookies are golden and set at the edges and still slightly soft in the center. Repeat with all cookie dough.
Cool cookies on baking sheet for 10 minutes before transferring them to a wire rack to cool completely.