In the bowl of a stand mixer fitted with the paddle attachment, add the peanut butter and sugar. Mix on medium speed for about 2 minutes, scraping down the sides of the bowl halfway through. The mixture should look smooth, thick, and slightly fluffy.

Add the egg and sour cream to the bowl. Continue mixing on medium speed for another 2 minutes, until fully incorporated and the dough looks creamy and cohesive. Scrape down the sides and bottom of the bowl as needed to ensure everything is evenly mixed.

Add the baking soda, salt, and vanilla extract. Mix on low speed just until combined. Avoid overmixing at this stage to keep the cookies tender.

Cover the bowl with plastic wrap and refrigerate for 1 hour. Chilling helps the dough firm up, prevents excessive spreading, and improves the overall texture of the cookies.

Preheat the oven to 350°F and line a baking sheet with parchment paper. Using a medium cookie scoop (2-tablespoon cookie scoop), scoop the dough and roll it into balls. Place the dough balls about 2 inches apart on the prepared baking sheet. Use a fork to gently press down on each cookie, creating the classic crisscross pattern on top of each cookie. You could use a 1 tablespoon cookie scoop for smaller cookies, and adjust the baking time.

Bake for 12–15 minutes, or until the edges are set and the tops look slightly crackled. The centers will still be soft. Remove from the oven and let the cookies cool on the baking sheet for 2 minutes, then transfer them to a wire rack to cool completely.

For an extra indulgent touch, dip the cooled cookies halfway into chocolate ganache or drizzle ganache over the tops. Allow the chocolate to set completely before serving or storing.