COMBINE in a large mixing bowl butter, brown sugar, milk and vanilla and blend until smooth. Add egg and mix well.
COMBINE in a small bowl flour, salt and baking soda. Gradually add to peanut butter mixture and cream until blended. For easier handling, wrap dough in plastic wrap and place in refrigerator until chilled, at least 1 hour.
PREHEAT oven to 375 degrees and coat a cookie sheet with cooking spray. Using a cookie dough scoop or tablespoon, scoop dough into balls and roll. Coat with granulated sugar and place on cookie sheet about 2 inches apart. Dip a fork in water and crisscross the cookie to flatten.
BAKE at 375°F for 7-9 minutes or until lightly golden brown. Cool completely.
COMBINE in a medium bowl COOL WHIP Frosting and strawberry jam. Depending on the flavor, you may want to add strawberry extract and to add a little color, mix in coloring.
FILL a decorator bag with the strawberry filling or spread with an offset spatula onto bottom side of cookie. Top with another cookie and press together lightly.