Beat margarine and peanut butter at medium speed of an electric mixer until creamy. Gradually add sugar, beating well. Add egg whites and vanilla; beat well. Combine flour, soda, and salt in a small bowl, stirring well. Gradually add flour mixture to creamed mixture, mixing well.
Shape dough into 40 (1-inch) balls. Place balls 2 inches apart on cookie sheets coated with cooking spray. Flatten cookies into 2-inch circles using a flat-bottomed glass. Bake at 350° for 8 minutes or until lightly browned. Cool slightly on cookie sheets; remove from cookie sheets, and let cool completely on wire racks.
Spread about 1 1/2 teaspoons strawberry spread on the bottom of half the cooled cookies; top with remaining cookies.