Make the cookies: Preheat oven to 350 degrees. Whisk together flour, baking soda, and salt; set aside.
Beat butter and sugar with an electric mixer on medium-high speed until light and fluffy, 2 to 3 minutes. Add egg and vanilla; beat until smooth. Reduce speed to low and gradually beat in flour mixture.
Scoop batter using a flat (not mounded) 1-inch ice cream scoop; space 2 inches apart on parchment-lined baking sheets. Bake about 12 minutes, or until golden brown.
Make the ganache: Place chocolate in a heatproof bowl and set over a pot of simmering water on low heat. Stir chocolate until melted. Remove from heat, and whisk in jam and heavy cream. Cover and chill 2 hours, or until cold. Transfer ganache to a piping bag fitted with a 1/4-inch star tip (such as Ateco #19). Pipe 2 teaspoons ganache on the outside edge of each cookie. Fill the center of the cookie with 2 to 3 raspberry halves. Sandwich with another cookie.