Follow these steps carefully to ensure your cookies turn out perfectly every time. Precision in baking often leads to the best results!

1. Preheat and Prepare: Preheat your oven to 350°F (175°C). Line two large baking sheets with parchment paper or silicone baking mats. This prevents sticking and helps with even baking.
2. Cream Butter and Sugars: In a large mixing bowl, using an electric mixer (stand mixer with a paddle attachment or a hand mixer), beat the softened unsalted butter, creamy peanut butter, granulated sugar, and packed light brown sugar together on medium speed until the mixture is light, fluffy, and well combined. This process, known as creaming, usually takes about 2-3 minutes. Scrape down the sides and bottom of the bowl occasionally to ensure everything is incorporated.
3. Add Eggs and Vanilla: Beat in the large eggs one at a time, mixing well after each addition until fully incorporated. Then, stir in the vanilla extract. The mixture should look smooth and emulsified.
4. Combine Dry Ingredients: In a separate medium-sized bowl, whisk together the all-purpose flour, rolled oats, baking soda, and salt. This ensures the leavening agent and salt are evenly distributed throughout the flour, leading to consistent cookies.
5. Combine Wet and Dry Mixtures: Gradually add the dry ingredient mixture to the wet ingredient mixture in the large bowl. Mix on low speed (or by hand with a sturdy spatula) until just combined. Be careful not to overmix at this stage; overmixing can lead to tough cookies. The dough will be thick.
6. Stir in Optional Add-ins: If you’re using chocolate chips or any other add-ins like chopped nuts, gently fold them into the cookie dough using a spatula until they are evenly distributed.
7. Portion the Dough: Drop rounded tablespoons of dough (about 1.5 to 2 tablespoons each) onto the prepared baking sheets, spacing them about 2 inches apart to allow for spreading. A cookie scoop is excellent for uniform sizing.
8. Create Criss-Cross Pattern (Optional but Classic): For the traditional peanut butter cookie look, dip a fork in a little granulated sugar (to prevent sticking) and gently press down on each ball of dough, first in one direction and then perpendicularly to create a criss-cross pattern. You can skip this if you prefer a more rustic look.
9. Bake: Bake in the preheated oven for 10-14 minutes, or until the edges are lightly golden brown and the centers are just set. The exact baking time will depend on your oven and the size of your cookies. For chewier cookies, err on the side of slightly underbaking.
10. Cool: Let the cookies cool on the baking sheets for 5-10 minutes. They will be quite soft when they first come out of the oven and will firm up as they cool. This initial cooling on the pan helps them set.
11. Transfer and Cool Completely: After 5-10 minutes, carefully transfer the cookies to a wire rack to cool completely. This prevents the bottoms from becoming soggy.
12. Store: Once completely cooled, store the peanut butter oat cookies in an airtight container at room temperature.