Combine flour, baking soda ,and salt in a small bowl and whisk together.
In a large bowl, using an electric mixer on medium speed, beat the margarine until light, approximately 1 minute. Beat in the sugar substitute, brown sugar substitute, brown sugar, egg, and vanilla extract. Beat until fluffy.
Stir in the flour mixture.
Stir in the chocolate chips.
Drop the dough by well-rounded tablespoons onto ungreased cookie sheets, flattening the mounds slightly so they will spread.
Bake until lightly golden, 8 to 10 minutes. Cool on the baking sheet for 5 minutes. Transfer to racks to cool completely.