1. Heat oven to 350 degrees F. In bowl, mix 1-3/4 cups flour and salt.
2. In separate bowl, beat sugar, butter, egg until creamy, 1 minute. Stir in flour mixture. Divide dough in half. Stir remaining 1/4 cup flour into one half. Stir cocoa powder into other half. Shape dough into balls, using 2 teaspoonfuls for each. Place, 1-1/2 inches apart, on ungreased baking sheets. Make indentation in center of each with thumb.
3. Bake in 350 degrees F oven for 12 to 14 minutes, until set. Press down indentations, if puffed. Transfer to wire racks; let cool.Filling:
4. In bowl, beat cheese, sugar and extract until smooth. Divide in half. Beat chocolate into one half. Transfer fillings to 2 separate plastic food-storage bags. Snip off corner from each. Fill centers of cookies, alternating colors.