With these jelly-filled cookies, even very young chefs can make their mark on cookie dough. For other filling options, try pressing a few chocolate chips, a couple of M&M's, or a chocolate kiss into the just-baked cookies.
In a large bowl, using a wooden spoon, cream the butter and brown sugar together until smooth. Stir in the egg and vanilla extract until combined.
Gradually stir in the flour and salt. Cover the dough and refrigerate it for at least 1 to 2 hours or until the dough is firm enough to roll into balls.
Heat the oven to 350. Form scant tablespoonfuls of the dough into 1-inch balls. Roll the balls in a bowl of granulated sugar. Place the balls on an ungreased baking sheet, leaving 2 inches between them.
Using your thumb, your knuckle, or the end of a wooden spoon, press an indentation into the center of each cookie. If the cookie cracks, just press the crack together to make it smooth. Fill the center of each cookie with about 1/2 teaspoon of jelly. Bake for 10 to 12 minutes or until very lightly browned.
Cool on the baking sheets for about 2 minutes. Using a metal spatula, transfer the cookies to a wire rack to cool completely. Repeat until all the dough is used.
These cookies can be prepared up to 1 week ahead of time and stored in an airtight container at room temperature. Makes about 4 dozen Jolly Thumbprints.
KIDS' STEPS: Kids can mix and measure ingredients, roll the dough into balls, make thumbprints, and fill cookies with their favorite flavor of jelly or preserves.