Preheat Oven: Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper.

Mix Wet Ingredients: In a large mixing bowl, combine the peanut butter, granulated sugar, brown sugar, egg, and vanilla extract. Mix until smooth and well combined.

Add Dry Ingredients: Stir in the baking soda, salt, and flour until just combined. The dough will be thick.

Shape the Cookies: Using a cookie scoop or tablespoon, portion out the dough and roll it into balls. If desired, roll the dough balls in granulated sugar for extra sweetness and texture.

Create Indentations: Place the dough balls on the prepared baking sheet, spacing them about 2 inches apart. Use your thumb or the back of a spoon to create a small indentation in the center of each cookie.

Add Jelly: Fill each indentation with about 1/2 teaspoon of jelly or jam.

Bake: Bake in the preheated oven for 10-12 minutes, or until the edges are lightly golden. The cookies will be soft but will firm up as they cool.

Cool: Allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.