Preheat the oven to 350°F (175°C). Line two baking sheets with parchment paper or silicone baking mats.
In a large mixing bowl, combine the cake mix, peanut butter, vegetable oil, and eggs. Stir with a wooden spoon or silicone spatula until a thick, uniform dough forms.
Scoop out 1 tablespoon of dough and roll it into a ball between your palms. Repeat with the remaining dough to yield about 24 balls.
Place the granulated sugar in a shallow dish. Roll each dough ball in the sugar until lightly coated, then place them 2 inches apart on the prepared baking sheets.
Use a fork to gently press down on each ball in a crisscross pattern, flattening them slightly.
Bake in the preheated oven for 10–12 minutes, or until the edges are lightly golden and the centers are set.
Remove the cookies from the oven and let them cool on the baking sheets for 5 minutes before transferring them to a wire rack to cool completely.
For best results, make sure your eggs are at room temperature and the peanut butter is creamy not natural or oily. If the dough feels too sticky, chill it in the fridge for 10–15 minutes before rolling. This helps the cookies hold their shape while baking and gives them a better texture.